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Elucidating the Effect of Static Electric Field on Amyloid Beta 1–42 Supramolecular Assembly
Journal Pre-proof Elucidating the effect of static electric field on Amyloid Beta 1–42 supramolecular assembly S. Muscat, F. Stojceski, A. Danani PII:
S1093-3263(19)30635-7
DOI:
https://doi.org/10.1016/j.jmgm.2020.107535
Reference:
JMG 107535
To appear in:
Journal of Molecular Graphics and Modelling
Received Date: 21 August 2019 Revised Date:
6 December 2019
Accepted Date: 9 January 2020
Please cite this article as: S. Muscat, F. Stojceski, A. Danani, Elucidating the effect of static electric field on Amyloid Beta 1–42 supramolecular assembly, Journal of Molecular Graphics and Modelling (2020), doi: https://doi.org/10.1016/j.jmgm.2020.107535. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Elucidating the Effect of Static Electric Field on Amyloid Beta 142 Supramolecular Assembly 1
1
1*
Muscat S. , Stojceski F. , and Danani A. . 1
Dalle Molle Institute for Artificial Intelligence (IDSIA), University of Italian Switzerland (USI), University of Applied
Science and Art of Southern Switzerland (SUPSI), Manno, Switzerland
Abstract Amyloid-β (Aβ) aggregation is recognized to be a key toxic factor in the pathogenesis of Alzheimer disease, which is the most common progressive neurodegenerative disorder. In vitro experiments have elucidated that Aβ aggregation depends on several factors, such as pH, temperature and peptide concentration. Despite the research effort in this field, the fundamental mechanism responsible for the disease progression is still unclear. Recent research has proposed the application of electric fields as a non-invasive therapeutic option leading to the disruption of amyloid fibrils. In this regard, a molecular level understanding of the interactions governing the destabilization mechanism represents an important research advancement. Understanding the electric field effects on proteins, provides a more in-depth comprehension of the relationship between protein conformation and electrostatic dipole moment. The present study focuses on investigating the effect of static Electric Field (EF) on the conformational dynamics of Aβ fibrils by all-atom Molecular Dynamics (MD) simulations. The outcome of this work provides novel insight into this research field, demonstrating how the Aβ assembly may be destabilized by the applied EF. Keywords: static electric field, amyloid beta, Alzheimer Disease, molecular dynamics, dipole moment, fibril detachment, supramolecular assembly, computational modelling. * Corresponding author. Tel.: +41 (0)58 666 65 68. E-mail address: [email protected]
Introduction Proteins are essential biomolecules involved in every physiologically relevant biochemical or biophysical process. Endogenous folding pathway which allows the achievement of proteins native conformational arrangement is strongly correlated to their biological activity [1]. A failure of the folding pathway may be related to genetic mutations, protein transcription error and misfolding, which may either result in a “loss-of-function” or a toxic “gain-of-function” mechanism [2]. In detail, protein misfolding occurs when the protein gets trapped in an off-pathway potential energy minimum that leads to a series of stable intermediates, which may culminate in the formation of toxic aggregates [3]. Several environmental factors which are able to perturb the protein folding mechanism have been studied in the past such as temperature [4], pH [5,6], pressure [7], mechanical forces [8], peptide concentration or solvents [9]. An increasing number of neurodegenerative disorders, including Alzheimer’s (AD), Huntington’s (HD) and Parkinson’s Diseases (PD) are directly related to the abnormal aggregation of misfolded amyloidogenic proteins [10–12]. In this context, the amyloid hypothesis proposes Aβ as the main cause of the AD [13]. This hypothesis suggests that the misfolding of the extracellular Aβ protein accumulated in senile plaques and the intracellular deposition of the misfolded tau protein in neurofibrillary tangles cause memory loss and confusion, leading in personality and cognitive decline over time [14]. While the exact cause of these diseases remains still unclear, disaggregating amyloid fibrils has emerged as one of the most important therapeutic strategies [15,16]. Enormous efforts to design an effective clinical agent have been concentrated on three different strategies: design of inhibitors of endosomal β-secretase responsible for the Aβ production [17], prevent the proteolytic cleavage of APP into Aβ [18] and clear various Aβfibrillar aggregates from the brain [19]. However, attractive therapeutic strategies such as Aβ breaker peptides [20] and active or passive immunotherapy have been associated with several problems including, brain haemorrhage, meningoencephalitis [21] and poor permeability through the blood-brain barrier (BBB) [22]. Recently, in order to overcome the low BBB permeability, researchers have accelerated the initiative of developing non-invasive solutions for the AD. It has been shown that when microwave radiation is applied, the aggregation in vitro of bovine serum albumin depends on time and temperature [23]. The disruption of BBB by ultrasound has shown a more effective removal of amyloid-β plaques, leading to a restored functional memory [24]. In a similar way, femtosecond laser [25], UV-light [26] and ultrasonic treatment (UST) [27] have been used to develop inhibitors/regulators of amyloidogenic aggregation. In this context, several studies have investigated the effects of external electric and magnetic fields, showing structural changes in various proteins and peptides due to the protein dipole alignment along the direction of the applied field [16,28,37–43,29– 36]. The application of alternating EFs (100-300 kHz) has demonstrated the inhibitor effect on the growth of human and mouse tumor cell lines [44], and also in vivo regarding the human brain cancer [45]. Although experimental methods could partly provide detailed information about protein behaviours due to the difficulty of taking measurements simultaneously with the application of the EF [46].
2
During the last decade, computer simulations have demonstrated to be useful in understanding complex phenomena such as the protein folding [47], protein-protein aggregation [48], and proteinbiological system interactions [49–51]. Computational modelling has been widely used to evaluate the dynamic and structural changes of proteins under the EF influence, as detailed in the following. Solomentsev et al. shown the conformational states perturbation of a short alanine-based peptide exposed under an EF with a strength greater than 0.1 V/nm [36]. Another study carried out MD simulations to evaluate the effects of static and pulsed electric fields (ranging from 1 V/nm to 0.1 V/nm) on a single myoglobin molecule [28], observing high denaturation for the higher intensity and no appreciable unfolding for the smaller intensity. Long-time simulations up to 1 µs have been performed on insulin and a loss of secondary structure has been observed with an EF intensity of 0.25 V/nm [29]. Alizadeh et al. carried out MD simulations to study systematically the deconstruction of human connexin26 hemichannel under the influence of static and alternating fields [31]. They reported that the lowest field (0.1 V/nm) does not produce relevant effects, while the highest field (1 V/nm) is able to deconstruct the hemichannel only in the case of a static electric field. Furthermore, novel research has highlighted the influence of intense EFs on tubulin dimer, showing the protein packing transition and elongation [35]. The Aβ protein, which is recognized to play a key role in the development of the AD, have been extensively studied [33,34,39,40,52–54]. However, all-atom molecular simulations of external EF effect on Aβ have been carried out only on monomer [39], dimer [33,34], up to pentamer [40]. In the present study, we systematically investigated the application of static EFs on an Aβ1-42 supramolecular assembly composed by a pentamer and a tetramer. In order to characterize Aβ assembly electrostatic behaviour at molecular level, EF strengths, ranging from 0 V/nm to 0.5 V/nm, have been tested. Our results suggest that the EFs induce a permanent or temporary dipole responsible for a conformational transition in the protein structure due to the mechanical stress produced on the charged peptides.
Materials and Methods Molecular Dynamics Set Up The atomic structure of the Aβ1-42 sequence (PDBID: 5OQV) [55] composed of two intertwined protofilaments (pentamer + tetramer) subsequently indicated as fibrillar complex or fibril, was selected as starting point of the present study. Explicitly represented water molecules were added to fill the +
−
system in a periodic cubic box (side 12 nm). Na and Cl ions were added to maintain physiological salinity (150 mM) and to obtain a neutral total charge of about 120˙000 interacting particles. All systems simulated were first minimized by applying steep descend algorithm. All subsequent operations were performed five times in order to increase the statistics of MD data. The systems were gradually equilibrated under position restrains, heating to 300 K ( ps in a NVT ensemble, and subsequently in a NPT ensemble at 1 atm (
= 0.1) for 200
= 2.0) for 200 ps. V-rescale
[56] and isotropic Berendsen [57] coupling methods were used as temperature and pressure coupling. Starting from the last frame of the equilibration, production simulation was performed for 100 ns using 3
the NPT ensemble under a constant temperature of 300 K (
= 0.1) and pressure of 1 atm (
= 5.0),
using respectively V-rescale [56] and Parrinello-Rahman [58] coupling methods. Furthermore, an external static EF was applied along the Y direction of the box for each system, simulating the following amplitudes: 0 V/nm, 0.2 V/nm, 0.25 V/nm, 0.3 V/nm, 0.4 V/nm and 0.5 V/nm. In detail, such EF intensities have been chosen, in line with previous computational works [32,39], because they are inside the general linear-response range of water (0.3–0.5 V/nm) [42,59,60] and they are below 1 V/nm, where the water structure may become instable [61,62]. A time step of 2 fs was used together with LINCS constraints [63]. The system topology was parameterized using the non-polarizable Amber ff99SB-ILDN force field [64] with TIP3P water model [65]. In detail, TIP3P is a fixed charge model composed by three interacting sites, widely used for simulations of biological and inorganic molecules with static or oscillating electric fields [37,61,66–73]. The use of fixed charge model for the protein force field is a limit of this manuscript. In literature, several polarizable force fields [74–76] have been developed to better take into account the bio-molecular electrostatics modelling and the effect of electronic polarization due to the electric field [77]. However, the simulation performance for the polarizable force field are significantly lower than non-polarizable one [78]. In this connection, the reliable computational prediction of protein dynamics requires a fair compromise between force field accuracy and deep sampling of the phase space by long molecular simulations. All MD simulations were performed by using the GROMACS 2018 package [79]. The Visual Molecular Dynamics (VMD) software was used to monitor and visually inspect all simulation trajectories [80]. This work evaluates the EF influence on (a) the fibrillar complex until the pentamer-tetramer detachment, and after on (b) the protofibrillar pentamer only. The analysis on the pentamer are computed considering the last 20 ns of MD trajectory. The trend versus time of each parameter analysed is reported in Supplementary Figure S1. A schematic summary of the simulated systems is reported in Supporting Information (Table S1).
Order Parameter Design In order to better quantify the influence of the EF on the pentamer assembly, an order parameter (ordP) was designed:
=
∑
(∑
(
)∙(
))
!
(1)
Here the arrow represents the connecting vector of the chain centre of mass (CoM) position and alpha carbon (Cα) position of the n-th residue and of the c-th chain. The ordP is the dot product averaged along the observation time interval, the number of residues (NR) and the number of the chains (NC). Values of ordP close to 1 indicated an alignment close to the initial structure, i.e., aligned fibre along the fibril axis z. Values of ordP lower than 1 indicated a gradual structure distortion (also refer to Supplementary Figure S2).
4
Dipole Moment The proteins have a natural electric dipole moment, characterized by the geometric arrangement in the space of the amino acid residues and by their electric charge. The dipole moment ( ) is defined as:
= ∑#%& "# where "# and
$
$
(2)
are the charge and vector position of the i-th atom respectively and N is the total
number of atoms.
Results and Discussion In this work the EFs effects on structural and electrostatic properties of Aβ1-42 peptides are systematically investigated. The first section focuses on the influence of the EF on the Aβ1-42 fibrillar complex, while in the second section the conformational stability of the pentameric component only is investigated. The results are reported for all the tested EF intensities and without the application of the external field as comparison system.
Rupture of the Fibrillar Complex The polymorphism of Aβ1-42 peptide is well studied in literature and recent researches have demonstrated the higher stability of the S-shape model compared to the U-shape model [52,53,81]. For this reason, in this work we have selected a S-shape model. In absence of EF, the protein complex is very stable as demonstrated by the RMSD of five replicas of 100 ns (Supplementary Figure S3). The EF is applied in the same direction (along Y coordinate) in all simulations. In Figure 1 we show a schematic representation of the global behaviour of the fibrillar complex. When the field is switched on, macroscopic and microscopic changes occur. Initially, there is a rearrangement of the chains structure in a simulation time that depends on EF intensity (middle of Figure 1). Subsequently in all simulations supramolecular assembly rupture occurs with the separation between the pentameric and tetrameric chains (end of Figure 1).
5
Figure 1: Schematic representation of pentamer and tetramer separation when EFs are applied.
The dipole moment components of pentamer and tetramer are reported in Figure 2 for the representative case of 0.3 V/nm intensity and compared with the molecular system without any applied EF. In Figure 2A-C the average and standard deviation values are referred about the last 5 ns of MD simulations. At the zero electric field strength, the effective Aβ fibril total dipole moment fluctuates around 327 debye (Figure 2A). The pentamer and the tetramer with 0 V/nm show opposite contributions in the X and Y directions and concorded contributions in Z direction (along fibrillar axis). Such behaviour is due to the mirror arrangement of the chains belonging to the pentamer and to the tetramer, respectively. The application of the EF leads to the alignment of the X and Y component in the pentamer and tetramer structure (Figure 2C). Furthermore, each component amplitude of dipole moment records an increase in value with EF application as already reported in literature [16,30,35,40], leading to the total dipole moment of fibrillar complex from an average value of (327 ± 156) debye to (2449 ± 118) debye. The same molecular mechanism has been observed for each investigated EF intensity (Supplementary Figure S4). The alignment of the dipole moment of each protofibril results in the increase of the total dipole moment. This molecular event leads to the first step of the fibril destabilization mechanism. After a certain time of EF application, where Aβ fibril adjusts and aligns the dipole moment, the separation between the pentamer and the tetramer takes 6
place as shown in Figure 1. This disrupting mechanism is based on a simple argument that conformational modification of the Aβ fibril is directly correlated to the reorientation and the increased intensity of the total dipole moment. More precisely, conformations with larger dipole moments gain more in statistical weight because of interactions with the field than the states with the lower moments do. When the dipole moment reaches a critical value, rupture between the two intertwined protofilaments is promoted. In literature, it is known that the change and the orientation rearrangement of the dipole moment plays a crucial role in the Aβ destabilization process [82]. In fact, the dipole moment influences the protein-protein or peptide-peptide interactions and represents a good descriptor of mechanical stability of a supramolecular fibril assembly [83].
Figure 2: Total and dipole moment component with (A) no-field and (C) 0.3 V/nm applied for the pentamer, tetramer and fibrillar complex. In the right (B-D) a schematic representation of the result dipole moment is shown with a blue arrow for the pentamer and tetramer.
The separation time between pentamer and tetramer was reported in Figure 3 to evaluate the rupture kinetics at different EF intensities. The Aβ fibril is considered completely detached when the minimum distance between the pentamer and the tetramer exceeds the threshold value of 0.3 nm. The average and standard deviation values reported in Figure 3 are computed considering the five MD replicas. The separation time is closely related to the EF strength. For intensity values between 0.5 V/nm and 0.4 V/nm, the rupture is really fast (few ns). Decreasing the EF intensity, the time required to reach the detachment increases a lot. For EF intensity lower than 0.2 V/nm we don’t observe the rupture, thus we assume that there is a threshold value beyond which the break of two intertwined protofilaments is disadvantaged. The fibrillar detachment kinetics may also be affected by varying the water molecules content [84]. In this connection, further investigations about the rupture kinetics in 7
function of the box size does not lead in any relevant trend about detachment of the fibrillar complex (Supplementary Figure S5).
Figure 3: Time required to break the fibrillar complex, separating the pentamer from the tetramer in function of EF intesity. Each black star is an individual simulation replica (five for each EF intesity). The average and standard deviation value are indicated in red.
Conformational Changes at Atomistic Level – Protofibrillar Pentamer Focus The application of external EF introduces forces that act mostly on the charged residues and the natural dipoles present in the peptide. It is reasonable to hypothesize that the internal forces that stabilize the Aβ pentamer, try to compensate the distortion force applied by external EF [40]. In this section, we analyse the conformational behaviour of the pentameric assembly after the detachment, using the same EF intensities applied to the fibrillar complex. The Figure 4 shows a representative configuration of the system for different EF strengths. It is worth to mention that each configuration achieved is strictly dependent on the EF intensity. During 100 ns of MD simulation, the studied pentamer remains mostly structured with a small population of turn and coil structure in the absence of the field. When the EF intensity increases, pronounced changes occur with loss of beta-sheet secondary structure that are converted mainly into coil/turn structures and a little percentage into alpha-helix structure.
Figure 4: Pentamer representative configurations at different EF intensities. The peptides are shown in cartoon with β-sheets in yellow, α-helix in blue and in purple, turn in cyan and coil in silver.
The secondary structure motifs and location are fundamental characteristics for any protein conformation [1]. Therefore, Figure 5A shows the percentage of beta-structure which represents a key factor of stability for amylogenic fibrils [85]. The fraction of beta-structure without EF is (63 ± 1)% of 8
the Aβ-Pentamer, in agreement with previous computational studies [86]. In vitro experiments performed on body native trypsin protein, shows no noticeable difference in the field-exposed and non-exposed samples, suggesting a negligible effect on overall function of the trypsin molecule upon exposure to the applied field [30]. Such evidence may indicate that the amyloid fibrils, due to their highly ordered and β-sheet rich structure, are more sensitive to EF and suffer an increased conformational transition. In this context, recent MD investigation has been ascertained the static EF promotes the transition from beta-sheet structure into random coil or alpha-helix structure [87]. The beta sheet loss as a function of EF intensity highlights the role played by the EF in the destabilization mechanism of the Aβ1-42 fibrils. To better quantify the EF ability to destabilize fibrillar structure in Figure 5B a geometric order parameter (OrdP) is computed (see Materials and Methods). In the past, other order parameters have been designed to evaluate the destabilization level of Aβ [52]. In the absence of EF, the Aβ-Pentamer shows a high order intra/inter chain with an OrdP ≈ 1. Increasing the EF amplitude, we observed a marked decrease of the OrdP values, in agreement with the previously reported data about the protein secondary structure. As mentioned before, the EF activation introduces forces that act on the charges and the dipoles present in the simulation system. Within this context, the Figure 5C shows the total dipole moment of Aβ-Pentamer, highlighting the remarkably dependence of EF intensity with electric dipole. Without the EF the wild Aβ-Pentamer dipole moment is (373 ± 156) debye. The application of the EF involves a notable growth of dipole moment which can increase up to six times in the case of 0.5 V/nm with respect to the wild structure. The total dipole moment maximization would seem to be the leading force through the reorganization of Aβ-Pentamer. Other computational works have seen the increase of dipole moment and independence from EF direction [32,40]. The reverse trend between betastructure percentage and total dipole moment, increasing the EF intensity, can be explained considering the greater stiffness of the beta sheets compared to the random coil structure. Indeed, the Aβ-Pentamer tries to arrange itself in order to interact more closely with the electric field, losing betastructures [16,40]. In other terms the difference in the dipole moment of beta-sheet and coil/turn is the microscopic explanation of conversion between the two phases.
9
Figure 5: A) Beta-structure percentage, B) order parameter and C) total dipole moment of Aβ1-42-protofibrill pentamer as a function of electric field intensity. Each column reported the average and standard deviation value about five indipendent replicas, computed on the 20 ns of MD trajectory.
The previously mentioned results show that the application of EF can induce a transition from betasheet to random coil and can influence the structure and organization of Aβ1-42 protein, acting as a disaggregating agent. Similar results have been obtained very recently on Aβ1-40 by Zheng et al. [88] who observed fibril to oligomer transition using a straight field of 0.01 V/nm. The EF intensity required for the transition on a disaggregated state may seem higher than the biological relevant scale [16]. Recent computational evidences have stated out that no unfolded state population for globular protein 7
is present for field intensities below 4.7 10 V/m [37]. However, the time scale of these simulations are orders of magnitude different from experimental ones [30,41,88]. In this framework, Pandey et al. [89] has pointed out that static EF of 150-300 V/cm, can effectively retard tau protein aggregation and supramolecular assembly of the core peptide segment in neuronal cell lines. Similarly, Saikia et al. [30] has performed in vitro experiments of Aβ1-42 protein with static EF at 150-300 V/cm, observing a decrease in the population of the highly ordered oligomers and fibrils towards lower order one. Previous computational investigations have demonstrated that EF strength lower than 0.1 V/nm does not alter significantly the overall structure of proteins within 100 ns MD simulations [29,36,61,90]. The
10
hypothesis is that the results obtained with small amplitude and experimental time scale are comparable with computational results using a higher amplitude and a shorter-time scale. In this section we have shown the close correlation between conformational changes and dipole moment as a function of EF intensity. Furthermore, the EF can lead to the rupture of Aβ fibril and can also destabilize the pentameric protofibril, exhibiting a speed up of the disruptive behaviour as the EF magnitude increases.
Conclusion Several neurodegenerative disorders are related to the deposition of protein aggregates in tissues where Aβ1-42 protein plays a key role in Alzheimer’s Disease. The aim of this work was to study at molecular level the influence of an external static EF on Aβ1-42 fibril. Overall, our results have shown that the application of EFs significantly perturbs the conformational structure of a well order protein. In particular, we have observed the rupture of a Aβ supramolecular assembly caused by protein chains rearrangement and increase of dipole moment. Furthermore, we have remarked the fundamental role of beta-sheet structure in stabilizing the amyloidogenic aggregates and how the activation of the EF leads in a decrease of beta-sheet percentage. In this context, the orientation and the amplitude of the dipole moment is a good indicator of overall structural stability. However, it is well known the polymorphism which characterizes the AD responsible proteins [91] may alter the effects of the external EF depending on the structure taken into consideration. Further in silico and in vitro experiments on the most common structure present in the amyloid plaques are needed in order to increase our knowledge on the effect of external EF in modulating the Aβ supramolecular assembly disaggregation.
Competing interests The authors declare no competing interests
Acknowledgements This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS).
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References [1]
C.M.
Dobson,
Protein
folding
and
misfolding,
Nature.
426
(2003)
884–890.
doi:10.1038/nature02261. [2]
L.M. Luheshi, D.C. Crowther, C.M. Dobson, Protein misfolding and disease: from the test tube to the organism, Curr. Opin. Chem. Biol. 12 (2008) 25–31. doi:10.1016/j.cbpa.2008.02.011.
[3]
T.C.T. Michaels, A. Šarić, J. Habchi, S. Chia, G. Meisl, M. Vendruscolo, C.M. Dobson, T.P.J. Knowles,
Chemical
Kinetics
for
Bridging
Molecular
Mechanisms
and
Macroscopic
Measurements of Amyloid Fibril Formation, Annu. Rev. Phys. Chem. 69 (2018) 273–298. doi:10.1146/annurev-physchem-050317-021322. [4]
O. Gursky, S. Aleshkov, Temperature-dependent β-sheet formation in β-amyloid Aβ1–40 peptide in water: uncoupling β-structure folding from aggregation, Biochim. Biophys. Acta Protein Struct. Mol. Enzymol. 1476 (2000) 93–102. doi:10.1016/S0167-4838(99)00228-9.
[5]
P.E. Fraser, J.T. Nguyen, W.K. Surewicz, D.A. Kirschner, pH-dependent structural transitions of Alzheimer amyloid peptides, Biophys. J. 60 (1991) 1190–1201. doi:10.1016/S00063495(91)82154-3.
[6]
W. Xu, C. Zhang, P. Derreumaux, A. Gräslund, L. Morozova-Roche, Y. Mu, Intrinsic Determinants
of
Computational
Aβ12–24 and
pH-Dependent
Experimental
Self-Assembly
Studies,
PLoS
Revealed
One.
6
by
Combined
(2011)
e24329.
doi:10.1371/journal.pone.0024329. [7]
J. Wiedersich, S. Köhler, A. Skerra, J. Friedrich, Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram,
Proc.
Natl.
Acad.
Sci.
U.
S.
A.
105
(2008)
5756–5761.
doi:10.1073/pnas.0710409105. [8]
M. Rief, Reversible Unfolding of Individual Titin Immunoglobulin Domains by AFM, Science (80-. ). 276 (1997) 1109–1112. doi:10.1126/science.276.5315.1109.
[9]
C.L. Shen, R.M. Murphy, Solvent effects on self-assembly of beta-amyloid peptide, Biophys. J. 69 (1995) 640–651. doi:10.1016/S0006-3495(95)79940-4.
[10]
C.M. Dobson, B.E.P. Swoboda, M. Joniau, C. Weissman, The structural basis of protein folding and its links with human disease, in: C.M. Dobson, R.J. Ellis, A.R. Fersht (Eds.), Philos. Trans. R. Soc. B Biol. Sci., 2001: pp. 133–145. doi:10.1098/rstb.2000.0758.
[11]
C.L. Masters, R. Bateman, K. Blennow, C.C. Rowe, R.A. Sperling, J.L. Cummings, Alzheimer’s disease, Nat. Rev. Dis. Prim. 1 (2015) 15056. doi:10.1038/nrdp.2015.56.
[12]
F. Chiti, C.M. Dobson, Protein Misfolding, Functional Amyloid, and Human Disease, Annu. Rev. Biochem. 75 (2006) 333–366. doi:10.1146/annurev.biochem.75.101304.123901.
12
[13]
D.J. Selkoe, J. Hardy, The amyloid hypothesis of Alzheimer’s disease at 25 years, EMBO Mol. Med. 8 (2016) 595–608. doi:10.15252/emmm.201606210.
[14]
G.S.
Bloom,
Amyloid-β
and
Tau,
JAMA
Neurol.
71
(2014)
505.
doi:10.1001/jamaneurol.2013.5847. [15]
S. Giorgetti, C. Greco, P. Tortora, F.A. Aprile, Targeting amyloid aggregation: An overview of strategies and mechanisms, Int. J. Mol. Sci. 19 (2018). doi:10.3390/ijms19092677.
[16]
A. Baumketner, Electric field as a disaggregating agent for amyloid fibrils, J. Phys. Chem. B. 118 (2014) 14578–14589. doi:10.1021/jp509213f.
[17]
S. Ben Halima, S. Mishra, K.M.P. Raja, M. Willem, A. Baici, K. Simons, O. Brüstle, P. Koch, C. Haass, A. Caflisch, L. Rajendran, Specific Inhibition of β-Secretase Processing of the Alzheimer
Disease
Amyloid
Precursor
Protein,
Cell
Rep.
14
(2016)
2127–2141.
doi:10.1016/j.celrep.2016.01.076. [18]
T. Jonsson, J.K. Atwal, S. Steinberg, J. Snaedal, P. V. Jonsson, S. Bjornsson, H. Stefansson, P. Sulem, D. Gudbjartsson, J. Maloney, K. Hoyte, A. Gustafson, Y. Liu, Y. Lu, T. Bhangale, R.R. Graham, J. Huttenlocher, G. Bjornsdottir, O.A. Andreassen, E.G. Jönsson, A. Palotie, T.W. Behrens, O.T. Magnusson, A. Kong, U. Thorsteinsdottir, R.J. Watts, K. Stefansson, A mutation in APP protects against Alzheimer’s disease and age-related cognitive decline, Nature. 488 (2012) 96–99. doi:10.1038/nature11283.
[19]
K.G. Yiannopoulou, S.G. Papageorgiou, Current and future treatments for Alzheimer’s disease, Ther. Adv. Neurol. Disord. 6 (2013) 19–33. doi:10.1177/1756285612461679.
[20]
M.W. Beck, S.B. Oh, R.A. Kerr, H.J. Lee, S.H. Kim, S. Kim, M. Jang, B.T. Ruotolo, J.Y. Lee, M.H. Lim, A rationally designed small molecule for identifying an in vivo link between metalamyloid-β complexes and the pathogenesis of Alzheimer’s disease, Chem. Sci. 6 (2015) 1879–1886. doi:10.1039/c4sc03239j.
[21]
J.M. Orgogozo, S. Gilman, J.F. Dartigues, B. Laurent, M. Puel, L.C. Kirby, P. Jouanny, B. Dubois, L. Eisner, S. Flitman, B.F. Michel, M. Boada, A. Frank, C. Hock, Subacute meningoencephalitis in a subset of patients with AD after Aβ42 immunization, Neurology. 61 (2003) 46–54. doi:10.1212/01.WNL.0000073623.84147.A8.
[22]
E. Zenaro, G. Piacentino, G. Constantin, The blood-brain barrier in Alzheimer’s disease, Neurobiol. Dis. 107 (2017) 41–56. doi:10.1016/j.nbd.2016.07.007.
[23]
D.I. de Pomerai, B. Smith, A. Dawe, K. North, T. Smith, D.B. Archer, I.R. Duce, D. Jones, E.P.M. Candido, Microwave radiation can alter protein conformation without bulk heating, FEBS Lett. 543 (2003) 93–97. doi:10.1016/S0014-5793(03)00413-7.
[24]
G. Leinenga, J. Götz, Scanning ultrasound removes amyloid-β and restores memory in an Alzheimer’s
disease mouse model, Sci. Transl. Med.
7 (2015)
278ra33-278ra33.
13
doi:10.1126/scitranslmed.aaa2512. [25]
D. Lin, R. He, S. Li, Y. Xu, J. Wang, G. Wei, M. Ji, X. Yang, Highly Efficient Destruction of Amyloid-β Fibrils by Femtosecond Laser-Induced Nanoexplosion of Gold Nanorods, ACS Chem. Neurosci. 7 (2016) 1728–1736. doi:10.1021/acschemneuro.6b00244.
[26]
T.J. Measey, F. Gai, Light-Triggered Disassembly of Amyloid Fibrils, Langmuir. 28 (2012) 12588–12592. doi:10.1021/la302626d.
[27]
W. Lee, H. Jung, M. Son, H. Lee, T.J. Kwak, G. Lee, C.H. Kim, S.W. Lee, D.S. Yoon, Characterization of the regrowth behavior of amyloid-like fragmented fibrils decomposed by ultrasonic treatment, RSC Adv. 4 (2014) 56561–56566. doi:10.1039/C4RA08270B.
[28]
P. Marracino, F. Apollonio, M. Liberti, G. D’Inzeo, A. Amadei, Effect of high exogenous electric pulses on protein conformation: Myoglobin as a case study, J. Phys. Chem. B. 117 (2013) 2273–2279. doi:10.1021/jp309857b.
[29]
X. Wang, Y. Li, X. He, S. Chen, J.Z.H. Zhang, Effect of strong electric field on the conformational
integrity
of
insulin,
J.
Phys.
Chem.
A.
118
(2014)
8942–8952.
doi:10.1021/jp501051r. [30]
J. Saikia, G. Pandey, S. Sasidharan, F. Antony, H.B. Nemade, S. Kumar, N. Chaudhary, V. Ramakrishnan, Electric Field Disruption of Amyloid Aggregation: Potential Noninvasive Therapy for Alzheimer’s Disease, ACS Chem. Neurosci. (2019) acschemneuro.8b00490. doi:10.1021/acschemneuro.8b00490.
[31]
H. Alizadeh, J. Davoodi, H. Rafii-Tabar, Deconstruction of the human connexin 26 hemichannel due to an applied electric field; A molecular dynamics simulation study, J. Mol. Graph. Model. 73 (2017) 108–114. doi:10.1016/j.jmgm.2017.02.006.
[32]
Z. Jiang, L. You, W. Dou, T. Sun, P. Xu, Effects of an Electric Field on the Conformational Transition of the Protein: A Molecular Dynamics Simulation Study, Polymers (Basel). 11 (2019) 282. doi:10.3390/polym11020282.
[33]
Y. Lu, X.F. Shi, F.R. Salsbury, P. Derreumaux, Small static electric field strength promotes aggregation-prone
structures
in
amyloid-β(29-42),
J.
Chem.
Phys.
146
(2017).
doi:10.1063/1.4979866. [34]
Y. Lu, X.-F. Shi, F.R. Salsbury, P. Derreumaux, Influence of electric field on the amyloid- β (29-42) peptides embedded in a membrane bilayer, J. Chem. Phys. 148 (2018) 045105. doi:10.1063/1.5018459.
[35]
P. Marracino, D. Havelka, J. Průša, M. Liberti, J. Tuszynski, A.T. Ayoub, F. Apollonio, M. Cifra, Tubulin response to intense nanosecond-scale electric field in molecular dynamics simulation, Sci. Rep. 9 (2019) 10477. doi:10.1038/s41598-019-46636-4.
[36]
G.Y. Solomentsev, N.J. English, D.A. Mooney, Effects of external electromagnetic fields on the 14
conformational sampling of a short alanine peptide, J. Comput. Chem. 33 (2012) 917–923. doi:10.1002/jcc.22912. [37]
A. Amadei, P. Marracino, Theoretical-computational modelling of the electric field effects on protein unfolding thermodynamics, RSC Adv. 5 (2015) 96551–96561. doi:10.1039/c5ra15605j.
[38]
Y. Xie, C. Liao, J. Zhou, Effects of external electric fields on lysozyme adsorption by molecular dynamics simulations, Biophys. Chem. 179 (2013) 26–34. doi:10.1016/j.bpc.2013.05.002.
[39]
F. Toschi, F. Lugli, F. Biscarini, F. Zerbetto, Effects of Electric Field Stress on a β-Amyloid Peptide, J. Phys. Chem. B. 113 (2009) 369–376. doi:10.1021/jp807896g.
[40]
F. Lugli, F. Toschi, F. Biscarini, F. Zerbetto, Electric field effects on short fibrils of aβ amyloid peptides, J. Chem. Theory Comput. 6 (2010) 3516–3526. doi:10.1021/ct1001335.
[41]
N.K. Pandey, S. Mitra, M. Chakraborty, S. Ghosh, S. Sen, S. Dasgupta, S. DasGupta, Disruption of human serum albumin fibrils by a static electric field, J. Phys. D. Appl. Phys. 47 (2014). doi:10.1088/0022-3727/47/30/305401.
[42]
N.J. English, C.J. Waldron, Perspectives on external electric fields in molecular simulation: Progress, prospects and challenges, Phys. Chem. Chem. Phys. 17 (2015) 12407–12440. doi:10.1039/c5cp00629e.
[43]
N. Todorova, A. Bentvelzen, N.J. English, I. Yarovsky, Electromagnetic-field effects on structure and dynamics of amyloidogenic peptides, J. Chem. Phys. 144 (2016) 085101. doi:10.1063/1.4941108.
[44]
E.D. Kirson, Z. Gurvich, R. Schneiderman, E. Dekel, A. Itzhaki, Y. Wasserman, R. Schatzberger, Y. Palti, Disruption of Cancer Cell Replication by Alternating Electric Fields, Cancer Res. 64 (2004) 3288–3295. doi:10.1158/0008-5472.CAN-04-0083.
[45]
E.D. Kirson, V. Dbalý, F. Tovaryš, J. Vymazal, J.F. Soustiel, A. Itzhaki, D. Mordechovich, S. Steinberg-Shapira, Z. Gurvich, R. Schneiderman, Y. Wasserman, M. Salzberg, B. Ryffel, D. Goldsher, E. Dekel, Y. Palti, Alternating electric fields arrest cell proliferation in animal tumor models and human brain tumors, Proc. Natl. Acad. Sci. U. S. A. 104 (2007) 10152–10157. doi:10.1073/pnas.0702916104.
[46]
D. Barten, J. Mieke Kleijn, M.A. Cohen Stuart, Adsorption of a linear polyelectrolyte on a gold electrode, Phys. Chem. Chem. Phys. 5 (2003) 4258. doi:10.1039/b300229b.
[47]
G. Grasso, J.A. Tuszynski, U. Morbiducci, G. Licandro, A. Danani, M.A. Deriu, Thermodynamic and kinetic stability of the Josephin Domain closed arrangement: evidences from replica exchange molecular dynamics, Biol. Direct. 12 (2017) 2. doi:10.1186/s13062-016-0173-y.
[48]
G. Grasso, U. Morbiducci, D. Massai, J.A. Tuszynski, A. Danani, M.A. Deriu, Destabilizing the AXH Tetramer by Mutations: Mechanisms and Potential Antiaggregation Strategies, Biophys. J. 114 (2018) 323–330. doi:10.1016/j.bpj.2017.11.025. 15
[49]
G. Grasso, S. Muscat, M. Rebella, U. Morbiducci, A. Audenino, A. Danani, M.A. Deriu, Cell penetrating peptide modulation of membrane biomechanics by Molecular dynamics., J. Biomech. (2018). doi:10.1016/j.jbiomech.2018.03.036.
[50]
A. Basciu, G. Malloci, F. Pietrucci, A.M.J.J. Bonvin, A. V. Vargiu, Holo-like and Druggable Protein Conformations from Enhanced Sampling of Binding Pocket Volume and Shape, J. Chem. Inf. Model. 59 (2019) 1515–1528. doi:10.1021/acs.jcim.8b00730.
[51]
A. Atzori, G. Malloci, J.D. Prajapati, A. Basciu, A. Bosin, U. Kleinekathöfer, J. Dreier, A. V. Vargiu, P. Ruggerone, Molecular Interactions of Cephalosporins with the Deep Binding Pocket of
the
RND
Transporter
AcrB,
J.
Phys.
Chem.
B.
123
(2019)
4625–4635.
doi:10.1021/acs.jpcb.9b01351. [52]
G. Grasso, M. Rebella, S. Muscat, U. Morbiducci, J. Tuszynski, A. Danani, M. Deriu, Conformational Dynamics and Stability of U-Shaped and S-Shaped Amyloid β Assemblies, Int. J. Mol. Sci. 19 (2018) 571. doi:10.3390/ijms19020571.
[53]
G. Grasso, M. Rebella, U. Morbiducci, J.A. Tuszynski, A. Danani, M.A. Deriu, The Role of Structural Polymorphism in Driving the Mechanical Performance of the Alzheimer’s Beta Amyloid Fibrils, Front. Bioeng. Biotechnol. 7 (2019) 1–11. doi:10.3389/fbioe.2019.00083.
[54]
J. Razzokov, M. Yusupov, A. Bogaerts, Oxidation destabilizes toxic amyloid beta peptide aggregation, Sci. Rep. 9 (2019) 5476. doi:10.1038/s41598-019-41931-6.
[55]
L. Gremer, D. Schölzel, C. Schenk, E. Reinartz, J. Labahn, R.B.G. Ravelli, M. Tusche, C. Lopez-Iglesias, W. Hoyer, H. Heise, D. Willbold, G.F. Schröder, Fibril structure of amyloid-β(1– 42)
by
cryo–electron
microscopy,
Science
(80-.
).
358
(2017)
116–119.
doi:10.1126/science.aao2825. [56]
G. Bussi, D. Donadio, M. Parrinello, Canonical sampling through velocity rescaling, J. Chem. Phys. 126 (2007). doi:10.1063/1.2408420.
[57]
H.J.C. Berendsen, J.P.M. Postma, W.F. van Gunsteren,
a DiNola, J.R. Haak, Molecular
dynamics with coupling to an external bath, J. Chem. Phys. 81 (1984) 3684–3690. doi:10.1063/1.448118. [58]
M. Parrinello, A. Rahman, Polymorphic transitions in single crystals: A new molecular dynamics method, J. Appl. Phys. 52 (1981) 7182–7190. doi:10.1063/1.328693.
[59]
N.J. English, J.M.D. MacElroy, Hydrogen bonding and molecular mobility in liquid water in external
electromagnetic
fields,
J.
Chem.
Phys.
119
(2003)
11806–11813.
doi:10.1063/1.1624363. [60]
R. Reale, N.J. English, P. Marracino, M. Liberti, F. Apollonio, Dipolar response and hydrogenbond kinetics in liquid water in square-wave time-varying electric fields, Mol. Phys. 112 (2014) 1870–1878. doi:10.1080/00268976.2013.867081.
16
[61]
A. Budi, F.S. Legge, H. Treutlein, I. Yarovsky, Electric field effects on insulin chain-B conformation, J. Phys. Chem. B. 109 (2005) 22641–22648. doi:10.1021/jp052742q.
[62]
D. Xu, J.C. Phillips, K. Schulten, Protein response to external electric fields: Relaxation, hysteresis, and echo, J. Phys. Chem. 100 (1996) 12108–12121. doi:10.1021/jp960076a.
[63]
B. Hess, H. Bekker, H.J.C. Berendsen, J.G.E.M. Fraaije, LINCS: A linear constraint solver for molecular simulations, J. Comput. Chem. 18 (1997) 1463–1472. doi:10.1002/(SICI)1096987X(199709)18:12<1463::AID-JCC4>3.0.CO;2-H.
[64]
K. Lindorff-Larsen, S. Piana, K. Palmo, P. Maragakis, J.L. Klepeis, R.O. Dror, D.E. Shaw, Improved side-chain torsion potentials for the Amber ff99SB protein force field, Proteins Struct. Funct. Bioinforma. 78 (2010) 1950–1958. doi:10.1002/prot.22711.
[65]
W.L. Jorgensen, J. Chandrasekhar, J.D. Madura, R.W. Impey, M.L. Klein, Comparison of simple potential functions for simulating liquid water, J. Chem. Phys. 79 (1983) 926. doi:10.1063/1.445869.
[66]
Q. Zhang, Y. Han, L. Wu, Influence of electrostatic field on the adsorption of phenol on singlewalled carbon nanotubes: A study by molecular dynamics simulation, Chem. Eng. J. 363 (2019) 278–284. doi:10.1016/j.cej.2019.01.146.
[67]
J.A. Garate, A. Bernardin, Y. Escalona, C. Yanez, N.J. English, T. Perez-Acle, Orientational and Folding Thermodynamics via Electric Dipole Moment Restraining, J. Phys. Chem. B. 123 (2019) 2599–2608. doi:10.1021/acs.jpcb.8b09374.
[68]
M. Bernardi, P. Marracino, M. Liberti, J.-A. Gárate, C.J. Burnham, F. Apollonio, N.J. English, Controlling ionic conductivity through transprotein electropores in human aquaporin 4: a nonequilibrium molecular-dynamics study, Phys. Chem. Chem. Phys. 21 (2019) 3339–3346. doi:10.1039/C8CP06643D.
[69]
J.-A. Garate, N.J. English, J.M.D. MacElroy, Static and alternating electric field and distancedependent effects on carbon nanotube-assisted water self-diffusion across lipid membranes, J. Chem. Phys. 131 (2009) 114508. doi:10.1063/1.3227042.
[70]
Y. Xie, Y. Pan, R. Zhang, Y. Liang, Z. Li, Modulating protein behaviors on responsive surface by external electric fields: A molecular dynamics study, Appl. Surf. Sci. 326 (2015) 55–65. doi:10.1016/j.apsusc.2014.11.078.
[71]
B. Harish Vagadia, S.K. Vanga, A. Singh, V. Raghavan, Effects of thermal and electric fields on soybean trypsin inhibitor protein: A molecular modelling study, Innov. Food Sci. Emerg. Technol. 35 (2016) 9–20. doi:10.1016/j.ifset.2016.03.004.
[72]
Q.-L. Zhang, R.-Y. Yang, Fast transport of water molecules across carbon nanotubes induced by
static
electric
fields,
Chem.
Phys.
Lett.
644
(2016)
201–204.
doi:10.1016/j.cplett.2015.11.061.
17
[73]
J.J. Timmons, J. Preto, J.A. Tuszynski, E.T. Wong, Tubulin’s response to external electric fields
by
molecular
dynamics
simulations,
PLoS
One.
13
(2018)
e0202141.
doi:10.1371/journal.pone.0202141. [74]
Z. Jing, C. Liu, S.Y. Cheng, R. Qi, B.D. Walker, J.-P. Piquemal, P. Ren, Polarizable Force Fields for Biomolecular Simulations: Recent Advances and Applications, Annu. Rev. Biophys. 48 (2019) 371–394. doi:10.1146/annurev-biophys-070317-033349.
[75]
J.A. Lemkul, J. Huang, B. Roux, A.D. MacKerell, An Empirical Polarizable Force Field Based on the Classical Drude Oscillator Model: Development History and Recent Applications, Chem. Rev. 116 (2016) 4983–5013. doi:10.1021/acs.chemrev.5b00505.
[76]
J.W. Ponder, C. Wu, P. Ren, V.S. Pande, J.D. Chodera, M.J. Schnieders, I. Haque, D.L. Mobley, D.S. Lambrecht, R.A. DiStasio, M. Head-Gordon, G.N.I. Clark, M.E. Johnson, T. Head-Gordon, Current Status of the AMOEBA Polarizable Force Field, J. Phys. Chem. B. 114 (2010) 2549–2564. doi:10.1021/jp910674d.
[77]
F. Calvo, P. Dugourd, Folding of Gas-Phase Polyalanines in a Static Electric Field: Alignment, Deformations,
and
Polarization
Effects,
Biophys.
J.
95
(2008)
18–32.
doi:10.1529/biophysj.107.124685. [78]
J.A. Lemkul, B. Roux, D. Van Der Spoel, A.D. Mackerell, Implementation of extended Lagrangian dynamics in GROMACS for polarizable simulations using the classical Drude oscillator model, J. Comput. Chem. 36 (2015) 1473–1479. doi:10.1002/jcc.23937.
[79]
M.J. Abraham, T. Murtola, R. Schulz, S. Páll, J.C. Smith, B. Hess, E. Lindah, Gromacs: High performance
molecular
simulations
through
multi-level
parallelism
from
laptops
to
supercomputers, SoftwareX. 1–2 (2015) 19–25. doi:10.1016/j.softx.2015.06.001. [80]
W. Humphrey, A. Dalke, K. Schulten, VMD: Visual molecular dynamics, J. Mol. Graph. 14 (1996) 33–38. doi:10.1016/0263-7855(96)00018-5.
[81]
D.M.Á.V. Acosta, B.C. Vega, J.C. Basurto, L.G.F. Morales, M.C.R. Hernández, Recent advances by in silico and in vitro studies of amyloid-β 1-42 fibril depicted a S-shape conformation, Int. J. Mol. Sci. 19 (2018). doi:10.3390/ijms19082415.
[82]
G.G. Tartaglia, A. Cavalli, R. Pellarin, A. Caflisch, The role of aromaticity, exposed surface, and dipole moment in determining protein aggregation rates, Protein Sci. 13 (2004) 1939– 1941. doi:10.1110/ps.04663504.
[83]
M. Kouza, A. Banerji, A. Kolinski, I. Buhimschi, A. Kloczkowski, Role of Resultant Dipole Moment in Mechanical Dissociation of Biological Complexes, Molecules. 23 (2018) 1995. doi:10.3390/molecules23081995.
[84]
N.J. English, C.J. Waldron, Perspectives on external electric fields in molecular simulation: progress, prospects and challenges, Phys. Chem. Chem. Phys. 17 (2015) 12407–12440.
18
doi:10.1039/C5CP00629E. [85]
L.C. Serpell, P.E. Fraser, M. Sunde, [34] X-Ray fiber diffraction of amyloid fibrils, in: 1999: pp. 526–536. doi:10.1016/S0076-6879(99)09036-9.
[86]
Y. Zou, Z. Qian, Y. Chen, H. Qian, G. Wei, Q. Zhang, Norepinephrine Inhibits Alzheimer’s Amyloid-β Peptide Aggregation and Destabilizes Amyloid-β Protofibrils: A Molecular Dynamics Simulation
Study,
ACS
Chem.
Neurosci.
10
(2019)
1585–1594.
doi:10.1021/acschemneuro.8b00537. [87]
P. Ojeda-May, M.E. Garcia, Electric Field-Driven Disruption of a Native β-Sheet Protein Conformation and Generation of a Helix-Structure, Biophys. J. 99 (2010) 595–599. doi:10.1016/j.bpj.2010.04.040.
[88]
Y. Zheng, Q. Wang, X. Yang, W. Nie, L. Zou, X. Liu, K. Wang, Aptamer as a Tool for Investigating the Effects of Electric Field on Aβ 40 Monomer and Aggregates Using SingleMolecule
Force
Spectroscopy,
Anal.
Chem.
91
(2019)
1954–1961.
doi:10.1021/acs.analchem.8b04278. [89]
G. Pandey, S. Morla, H.B. Nemade, S. Kumar, V. Ramakrishnan, Modulation of aggregation with an electric field; Scientific roadmap for a potential non-invasive therapy against tauopathies, RSC Adv. 9 (2019) 4744–4750. doi:10.1039/c8ra09993f.
[90]
N. English, D. Mooney, Denaturation of hen egg white lysozyme in electromagnetic fields: A molecular dynamics study, 2007 NSTI Nanotechnol. Conf. Trade Show - NSTI Nanotech 2007, Tech. Proc. 1 (2007) 434–437. doi:10.1063/1.2515315.
[91]
M. Fändrich, S. Nyström, K.P.R. Nilsson, A. Böckmann, H. LeVine, P. Hammarström, Amyloid fibril polymorphism: a challenge for molecular imaging and therapy, J. Intern. Med. 283 (2018) 218–237. doi:10.1111/joim.12732.
19
Highlights
•
Systematic investigation of static electric field (EF) influence on Amyloid Beta 1-42 (Aβ142)
with molecular dynamics (MD) simulations.
•
The beta-sheet secondary structure is a key factor of Aβ stability.
•
The maximization of electric dipole moment is the driving force that lead to the amyloidbeta protein destabilization.
•
An external EF can be used as disaggregating agent of Aβ fibril.
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:
S1093-3263(19)30635-7
DOI:
https://doi.org/10.1016/j.jmgm.2020.107535
Reference:
JMG 107535
To appear in:
Journal of Molecular Graphics and Modelling
Received Date: 21 August 2019 Revised Date:
6 December 2019
Accepted Date: 9 January 2020
Please cite this article as: S. Muscat, F. Stojceski, A. Danani, Elucidating the effect of static electric field on Amyloid Beta 1–42 supramolecular assembly, Journal of Molecular Graphics and Modelling (2020), doi: https://doi.org/10.1016/j.jmgm.2020.107535. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Elucidating the Effect of Static Electric Field on Amyloid Beta 142 Supramolecular Assembly 1
1
1*
Muscat S. , Stojceski F. , and Danani A. . 1
Dalle Molle Institute for Artificial Intelligence (IDSIA), University of Italian Switzerland (USI), University of Applied
Science and Art of Southern Switzerland (SUPSI), Manno, Switzerland
Abstract Amyloid-β (Aβ) aggregation is recognized to be a key toxic factor in the pathogenesis of Alzheimer disease, which is the most common progressive neurodegenerative disorder. In vitro experiments have elucidated that Aβ aggregation depends on several factors, such as pH, temperature and peptide concentration. Despite the research effort in this field, the fundamental mechanism responsible for the disease progression is still unclear. Recent research has proposed the application of electric fields as a non-invasive therapeutic option leading to the disruption of amyloid fibrils. In this regard, a molecular level understanding of the interactions governing the destabilization mechanism represents an important research advancement. Understanding the electric field effects on proteins, provides a more in-depth comprehension of the relationship between protein conformation and electrostatic dipole moment. The present study focuses on investigating the effect of static Electric Field (EF) on the conformational dynamics of Aβ fibrils by all-atom Molecular Dynamics (MD) simulations. The outcome of this work provides novel insight into this research field, demonstrating how the Aβ assembly may be destabilized by the applied EF. Keywords: static electric field, amyloid beta, Alzheimer Disease, molecular dynamics, dipole moment, fibril detachment, supramolecular assembly, computational modelling. * Corresponding author. Tel.: +41 (0)58 666 65 68. E-mail address: [email protected]
Introduction Proteins are essential biomolecules involved in every physiologically relevant biochemical or biophysical process. Endogenous folding pathway which allows the achievement of proteins native conformational arrangement is strongly correlated to their biological activity [1]. A failure of the folding pathway may be related to genetic mutations, protein transcription error and misfolding, which may either result in a “loss-of-function” or a toxic “gain-of-function” mechanism [2]. In detail, protein misfolding occurs when the protein gets trapped in an off-pathway potential energy minimum that leads to a series of stable intermediates, which may culminate in the formation of toxic aggregates [3]. Several environmental factors which are able to perturb the protein folding mechanism have been studied in the past such as temperature [4], pH [5,6], pressure [7], mechanical forces [8], peptide concentration or solvents [9]. An increasing number of neurodegenerative disorders, including Alzheimer’s (AD), Huntington’s (HD) and Parkinson’s Diseases (PD) are directly related to the abnormal aggregation of misfolded amyloidogenic proteins [10–12]. In this context, the amyloid hypothesis proposes Aβ as the main cause of the AD [13]. This hypothesis suggests that the misfolding of the extracellular Aβ protein accumulated in senile plaques and the intracellular deposition of the misfolded tau protein in neurofibrillary tangles cause memory loss and confusion, leading in personality and cognitive decline over time [14]. While the exact cause of these diseases remains still unclear, disaggregating amyloid fibrils has emerged as one of the most important therapeutic strategies [15,16]. Enormous efforts to design an effective clinical agent have been concentrated on three different strategies: design of inhibitors of endosomal β-secretase responsible for the Aβ production [17], prevent the proteolytic cleavage of APP into Aβ [18] and clear various Aβfibrillar aggregates from the brain [19]. However, attractive therapeutic strategies such as Aβ breaker peptides [20] and active or passive immunotherapy have been associated with several problems including, brain haemorrhage, meningoencephalitis [21] and poor permeability through the blood-brain barrier (BBB) [22]. Recently, in order to overcome the low BBB permeability, researchers have accelerated the initiative of developing non-invasive solutions for the AD. It has been shown that when microwave radiation is applied, the aggregation in vitro of bovine serum albumin depends on time and temperature [23]. The disruption of BBB by ultrasound has shown a more effective removal of amyloid-β plaques, leading to a restored functional memory [24]. In a similar way, femtosecond laser [25], UV-light [26] and ultrasonic treatment (UST) [27] have been used to develop inhibitors/regulators of amyloidogenic aggregation. In this context, several studies have investigated the effects of external electric and magnetic fields, showing structural changes in various proteins and peptides due to the protein dipole alignment along the direction of the applied field [16,28,37–43,29– 36]. The application of alternating EFs (100-300 kHz) has demonstrated the inhibitor effect on the growth of human and mouse tumor cell lines [44], and also in vivo regarding the human brain cancer [45]. Although experimental methods could partly provide detailed information about protein behaviours due to the difficulty of taking measurements simultaneously with the application of the EF [46].
2
During the last decade, computer simulations have demonstrated to be useful in understanding complex phenomena such as the protein folding [47], protein-protein aggregation [48], and proteinbiological system interactions [49–51]. Computational modelling has been widely used to evaluate the dynamic and structural changes of proteins under the EF influence, as detailed in the following. Solomentsev et al. shown the conformational states perturbation of a short alanine-based peptide exposed under an EF with a strength greater than 0.1 V/nm [36]. Another study carried out MD simulations to evaluate the effects of static and pulsed electric fields (ranging from 1 V/nm to 0.1 V/nm) on a single myoglobin molecule [28], observing high denaturation for the higher intensity and no appreciable unfolding for the smaller intensity. Long-time simulations up to 1 µs have been performed on insulin and a loss of secondary structure has been observed with an EF intensity of 0.25 V/nm [29]. Alizadeh et al. carried out MD simulations to study systematically the deconstruction of human connexin26 hemichannel under the influence of static and alternating fields [31]. They reported that the lowest field (0.1 V/nm) does not produce relevant effects, while the highest field (1 V/nm) is able to deconstruct the hemichannel only in the case of a static electric field. Furthermore, novel research has highlighted the influence of intense EFs on tubulin dimer, showing the protein packing transition and elongation [35]. The Aβ protein, which is recognized to play a key role in the development of the AD, have been extensively studied [33,34,39,40,52–54]. However, all-atom molecular simulations of external EF effect on Aβ have been carried out only on monomer [39], dimer [33,34], up to pentamer [40]. In the present study, we systematically investigated the application of static EFs on an Aβ1-42 supramolecular assembly composed by a pentamer and a tetramer. In order to characterize Aβ assembly electrostatic behaviour at molecular level, EF strengths, ranging from 0 V/nm to 0.5 V/nm, have been tested. Our results suggest that the EFs induce a permanent or temporary dipole responsible for a conformational transition in the protein structure due to the mechanical stress produced on the charged peptides.
Materials and Methods Molecular Dynamics Set Up The atomic structure of the Aβ1-42 sequence (PDBID: 5OQV) [55] composed of two intertwined protofilaments (pentamer + tetramer) subsequently indicated as fibrillar complex or fibril, was selected as starting point of the present study. Explicitly represented water molecules were added to fill the +
−
system in a periodic cubic box (side 12 nm). Na and Cl ions were added to maintain physiological salinity (150 mM) and to obtain a neutral total charge of about 120˙000 interacting particles. All systems simulated were first minimized by applying steep descend algorithm. All subsequent operations were performed five times in order to increase the statistics of MD data. The systems were gradually equilibrated under position restrains, heating to 300 K ( ps in a NVT ensemble, and subsequently in a NPT ensemble at 1 atm (
= 0.1) for 200
= 2.0) for 200 ps. V-rescale
[56] and isotropic Berendsen [57] coupling methods were used as temperature and pressure coupling. Starting from the last frame of the equilibration, production simulation was performed for 100 ns using 3
the NPT ensemble under a constant temperature of 300 K (
= 0.1) and pressure of 1 atm (
= 5.0),
using respectively V-rescale [56] and Parrinello-Rahman [58] coupling methods. Furthermore, an external static EF was applied along the Y direction of the box for each system, simulating the following amplitudes: 0 V/nm, 0.2 V/nm, 0.25 V/nm, 0.3 V/nm, 0.4 V/nm and 0.5 V/nm. In detail, such EF intensities have been chosen, in line with previous computational works [32,39], because they are inside the general linear-response range of water (0.3–0.5 V/nm) [42,59,60] and they are below 1 V/nm, where the water structure may become instable [61,62]. A time step of 2 fs was used together with LINCS constraints [63]. The system topology was parameterized using the non-polarizable Amber ff99SB-ILDN force field [64] with TIP3P water model [65]. In detail, TIP3P is a fixed charge model composed by three interacting sites, widely used for simulations of biological and inorganic molecules with static or oscillating electric fields [37,61,66–73]. The use of fixed charge model for the protein force field is a limit of this manuscript. In literature, several polarizable force fields [74–76] have been developed to better take into account the bio-molecular electrostatics modelling and the effect of electronic polarization due to the electric field [77]. However, the simulation performance for the polarizable force field are significantly lower than non-polarizable one [78]. In this connection, the reliable computational prediction of protein dynamics requires a fair compromise between force field accuracy and deep sampling of the phase space by long molecular simulations. All MD simulations were performed by using the GROMACS 2018 package [79]. The Visual Molecular Dynamics (VMD) software was used to monitor and visually inspect all simulation trajectories [80]. This work evaluates the EF influence on (a) the fibrillar complex until the pentamer-tetramer detachment, and after on (b) the protofibrillar pentamer only. The analysis on the pentamer are computed considering the last 20 ns of MD trajectory. The trend versus time of each parameter analysed is reported in Supplementary Figure S1. A schematic summary of the simulated systems is reported in Supporting Information (Table S1).
Order Parameter Design In order to better quantify the influence of the EF on the pentamer assembly, an order parameter (ordP) was designed:
=
∑
(∑
(
)∙(
))
!
(1)
Here the arrow represents the connecting vector of the chain centre of mass (CoM) position and alpha carbon (Cα) position of the n-th residue and of the c-th chain. The ordP is the dot product averaged along the observation time interval, the number of residues (NR) and the number of the chains (NC). Values of ordP close to 1 indicated an alignment close to the initial structure, i.e., aligned fibre along the fibril axis z. Values of ordP lower than 1 indicated a gradual structure distortion (also refer to Supplementary Figure S2).
4
Dipole Moment The proteins have a natural electric dipole moment, characterized by the geometric arrangement in the space of the amino acid residues and by their electric charge. The dipole moment ( ) is defined as:
= ∑#%& "# where "# and
$
$
(2)
are the charge and vector position of the i-th atom respectively and N is the total
number of atoms.
Results and Discussion In this work the EFs effects on structural and electrostatic properties of Aβ1-42 peptides are systematically investigated. The first section focuses on the influence of the EF on the Aβ1-42 fibrillar complex, while in the second section the conformational stability of the pentameric component only is investigated. The results are reported for all the tested EF intensities and without the application of the external field as comparison system.
Rupture of the Fibrillar Complex The polymorphism of Aβ1-42 peptide is well studied in literature and recent researches have demonstrated the higher stability of the S-shape model compared to the U-shape model [52,53,81]. For this reason, in this work we have selected a S-shape model. In absence of EF, the protein complex is very stable as demonstrated by the RMSD of five replicas of 100 ns (Supplementary Figure S3). The EF is applied in the same direction (along Y coordinate) in all simulations. In Figure 1 we show a schematic representation of the global behaviour of the fibrillar complex. When the field is switched on, macroscopic and microscopic changes occur. Initially, there is a rearrangement of the chains structure in a simulation time that depends on EF intensity (middle of Figure 1). Subsequently in all simulations supramolecular assembly rupture occurs with the separation between the pentameric and tetrameric chains (end of Figure 1).
5
Figure 1: Schematic representation of pentamer and tetramer separation when EFs are applied.
The dipole moment components of pentamer and tetramer are reported in Figure 2 for the representative case of 0.3 V/nm intensity and compared with the molecular system without any applied EF. In Figure 2A-C the average and standard deviation values are referred about the last 5 ns of MD simulations. At the zero electric field strength, the effective Aβ fibril total dipole moment fluctuates around 327 debye (Figure 2A). The pentamer and the tetramer with 0 V/nm show opposite contributions in the X and Y directions and concorded contributions in Z direction (along fibrillar axis). Such behaviour is due to the mirror arrangement of the chains belonging to the pentamer and to the tetramer, respectively. The application of the EF leads to the alignment of the X and Y component in the pentamer and tetramer structure (Figure 2C). Furthermore, each component amplitude of dipole moment records an increase in value with EF application as already reported in literature [16,30,35,40], leading to the total dipole moment of fibrillar complex from an average value of (327 ± 156) debye to (2449 ± 118) debye. The same molecular mechanism has been observed for each investigated EF intensity (Supplementary Figure S4). The alignment of the dipole moment of each protofibril results in the increase of the total dipole moment. This molecular event leads to the first step of the fibril destabilization mechanism. After a certain time of EF application, where Aβ fibril adjusts and aligns the dipole moment, the separation between the pentamer and the tetramer takes 6
place as shown in Figure 1. This disrupting mechanism is based on a simple argument that conformational modification of the Aβ fibril is directly correlated to the reorientation and the increased intensity of the total dipole moment. More precisely, conformations with larger dipole moments gain more in statistical weight because of interactions with the field than the states with the lower moments do. When the dipole moment reaches a critical value, rupture between the two intertwined protofilaments is promoted. In literature, it is known that the change and the orientation rearrangement of the dipole moment plays a crucial role in the Aβ destabilization process [82]. In fact, the dipole moment influences the protein-protein or peptide-peptide interactions and represents a good descriptor of mechanical stability of a supramolecular fibril assembly [83].
Figure 2: Total and dipole moment component with (A) no-field and (C) 0.3 V/nm applied for the pentamer, tetramer and fibrillar complex. In the right (B-D) a schematic representation of the result dipole moment is shown with a blue arrow for the pentamer and tetramer.
The separation time between pentamer and tetramer was reported in Figure 3 to evaluate the rupture kinetics at different EF intensities. The Aβ fibril is considered completely detached when the minimum distance between the pentamer and the tetramer exceeds the threshold value of 0.3 nm. The average and standard deviation values reported in Figure 3 are computed considering the five MD replicas. The separation time is closely related to the EF strength. For intensity values between 0.5 V/nm and 0.4 V/nm, the rupture is really fast (few ns). Decreasing the EF intensity, the time required to reach the detachment increases a lot. For EF intensity lower than 0.2 V/nm we don’t observe the rupture, thus we assume that there is a threshold value beyond which the break of two intertwined protofilaments is disadvantaged. The fibrillar detachment kinetics may also be affected by varying the water molecules content [84]. In this connection, further investigations about the rupture kinetics in 7
function of the box size does not lead in any relevant trend about detachment of the fibrillar complex (Supplementary Figure S5).
Figure 3: Time required to break the fibrillar complex, separating the pentamer from the tetramer in function of EF intesity. Each black star is an individual simulation replica (five for each EF intesity). The average and standard deviation value are indicated in red.
Conformational Changes at Atomistic Level – Protofibrillar Pentamer Focus The application of external EF introduces forces that act mostly on the charged residues and the natural dipoles present in the peptide. It is reasonable to hypothesize that the internal forces that stabilize the Aβ pentamer, try to compensate the distortion force applied by external EF [40]. In this section, we analyse the conformational behaviour of the pentameric assembly after the detachment, using the same EF intensities applied to the fibrillar complex. The Figure 4 shows a representative configuration of the system for different EF strengths. It is worth to mention that each configuration achieved is strictly dependent on the EF intensity. During 100 ns of MD simulation, the studied pentamer remains mostly structured with a small population of turn and coil structure in the absence of the field. When the EF intensity increases, pronounced changes occur with loss of beta-sheet secondary structure that are converted mainly into coil/turn structures and a little percentage into alpha-helix structure.
Figure 4: Pentamer representative configurations at different EF intensities. The peptides are shown in cartoon with β-sheets in yellow, α-helix in blue and in purple, turn in cyan and coil in silver.
The secondary structure motifs and location are fundamental characteristics for any protein conformation [1]. Therefore, Figure 5A shows the percentage of beta-structure which represents a key factor of stability for amylogenic fibrils [85]. The fraction of beta-structure without EF is (63 ± 1)% of 8
the Aβ-Pentamer, in agreement with previous computational studies [86]. In vitro experiments performed on body native trypsin protein, shows no noticeable difference in the field-exposed and non-exposed samples, suggesting a negligible effect on overall function of the trypsin molecule upon exposure to the applied field [30]. Such evidence may indicate that the amyloid fibrils, due to their highly ordered and β-sheet rich structure, are more sensitive to EF and suffer an increased conformational transition. In this context, recent MD investigation has been ascertained the static EF promotes the transition from beta-sheet structure into random coil or alpha-helix structure [87]. The beta sheet loss as a function of EF intensity highlights the role played by the EF in the destabilization mechanism of the Aβ1-42 fibrils. To better quantify the EF ability to destabilize fibrillar structure in Figure 5B a geometric order parameter (OrdP) is computed (see Materials and Methods). In the past, other order parameters have been designed to evaluate the destabilization level of Aβ [52]. In the absence of EF, the Aβ-Pentamer shows a high order intra/inter chain with an OrdP ≈ 1. Increasing the EF amplitude, we observed a marked decrease of the OrdP values, in agreement with the previously reported data about the protein secondary structure. As mentioned before, the EF activation introduces forces that act on the charges and the dipoles present in the simulation system. Within this context, the Figure 5C shows the total dipole moment of Aβ-Pentamer, highlighting the remarkably dependence of EF intensity with electric dipole. Without the EF the wild Aβ-Pentamer dipole moment is (373 ± 156) debye. The application of the EF involves a notable growth of dipole moment which can increase up to six times in the case of 0.5 V/nm with respect to the wild structure. The total dipole moment maximization would seem to be the leading force through the reorganization of Aβ-Pentamer. Other computational works have seen the increase of dipole moment and independence from EF direction [32,40]. The reverse trend between betastructure percentage and total dipole moment, increasing the EF intensity, can be explained considering the greater stiffness of the beta sheets compared to the random coil structure. Indeed, the Aβ-Pentamer tries to arrange itself in order to interact more closely with the electric field, losing betastructures [16,40]. In other terms the difference in the dipole moment of beta-sheet and coil/turn is the microscopic explanation of conversion between the two phases.
9
Figure 5: A) Beta-structure percentage, B) order parameter and C) total dipole moment of Aβ1-42-protofibrill pentamer as a function of electric field intensity. Each column reported the average and standard deviation value about five indipendent replicas, computed on the 20 ns of MD trajectory.
The previously mentioned results show that the application of EF can induce a transition from betasheet to random coil and can influence the structure and organization of Aβ1-42 protein, acting as a disaggregating agent. Similar results have been obtained very recently on Aβ1-40 by Zheng et al. [88] who observed fibril to oligomer transition using a straight field of 0.01 V/nm. The EF intensity required for the transition on a disaggregated state may seem higher than the biological relevant scale [16]. Recent computational evidences have stated out that no unfolded state population for globular protein 7
is present for field intensities below 4.7 10 V/m [37]. However, the time scale of these simulations are orders of magnitude different from experimental ones [30,41,88]. In this framework, Pandey et al. [89] has pointed out that static EF of 150-300 V/cm, can effectively retard tau protein aggregation and supramolecular assembly of the core peptide segment in neuronal cell lines. Similarly, Saikia et al. [30] has performed in vitro experiments of Aβ1-42 protein with static EF at 150-300 V/cm, observing a decrease in the population of the highly ordered oligomers and fibrils towards lower order one. Previous computational investigations have demonstrated that EF strength lower than 0.1 V/nm does not alter significantly the overall structure of proteins within 100 ns MD simulations [29,36,61,90]. The
10
hypothesis is that the results obtained with small amplitude and experimental time scale are comparable with computational results using a higher amplitude and a shorter-time scale. In this section we have shown the close correlation between conformational changes and dipole moment as a function of EF intensity. Furthermore, the EF can lead to the rupture of Aβ fibril and can also destabilize the pentameric protofibril, exhibiting a speed up of the disruptive behaviour as the EF magnitude increases.
Conclusion Several neurodegenerative disorders are related to the deposition of protein aggregates in tissues where Aβ1-42 protein plays a key role in Alzheimer’s Disease. The aim of this work was to study at molecular level the influence of an external static EF on Aβ1-42 fibril. Overall, our results have shown that the application of EFs significantly perturbs the conformational structure of a well order protein. In particular, we have observed the rupture of a Aβ supramolecular assembly caused by protein chains rearrangement and increase of dipole moment. Furthermore, we have remarked the fundamental role of beta-sheet structure in stabilizing the amyloidogenic aggregates and how the activation of the EF leads in a decrease of beta-sheet percentage. In this context, the orientation and the amplitude of the dipole moment is a good indicator of overall structural stability. However, it is well known the polymorphism which characterizes the AD responsible proteins [91] may alter the effects of the external EF depending on the structure taken into consideration. Further in silico and in vitro experiments on the most common structure present in the amyloid plaques are needed in order to increase our knowledge on the effect of external EF in modulating the Aβ supramolecular assembly disaggregation.
Competing interests The authors declare no competing interests
Acknowledgements This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS).
11
References [1]
C.M.
Dobson,
Protein
folding
and
misfolding,
Nature.
426
(2003)
884–890.
doi:10.1038/nature02261. [2]
L.M. Luheshi, D.C. Crowther, C.M. Dobson, Protein misfolding and disease: from the test tube to the organism, Curr. Opin. Chem. Biol. 12 (2008) 25–31. doi:10.1016/j.cbpa.2008.02.011.
[3]
T.C.T. Michaels, A. Šarić, J. Habchi, S. Chia, G. Meisl, M. Vendruscolo, C.M. Dobson, T.P.J. Knowles,
Chemical
Kinetics
for
Bridging
Molecular
Mechanisms
and
Macroscopic
Measurements of Amyloid Fibril Formation, Annu. Rev. Phys. Chem. 69 (2018) 273–298. doi:10.1146/annurev-physchem-050317-021322. [4]
O. Gursky, S. Aleshkov, Temperature-dependent β-sheet formation in β-amyloid Aβ1–40 peptide in water: uncoupling β-structure folding from aggregation, Biochim. Biophys. Acta Protein Struct. Mol. Enzymol. 1476 (2000) 93–102. doi:10.1016/S0167-4838(99)00228-9.
[5]
P.E. Fraser, J.T. Nguyen, W.K. Surewicz, D.A. Kirschner, pH-dependent structural transitions of Alzheimer amyloid peptides, Biophys. J. 60 (1991) 1190–1201. doi:10.1016/S00063495(91)82154-3.
[6]
W. Xu, C. Zhang, P. Derreumaux, A. Gräslund, L. Morozova-Roche, Y. Mu, Intrinsic Determinants
of
Computational
Aβ12–24 and
pH-Dependent
Experimental
Self-Assembly
Studies,
PLoS
Revealed
One.
6
by
Combined
(2011)
e24329.
doi:10.1371/journal.pone.0024329. [7]
J. Wiedersich, S. Köhler, A. Skerra, J. Friedrich, Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram,
Proc.
Natl.
Acad.
Sci.
U.
S.
A.
105
(2008)
5756–5761.
doi:10.1073/pnas.0710409105. [8]
M. Rief, Reversible Unfolding of Individual Titin Immunoglobulin Domains by AFM, Science (80-. ). 276 (1997) 1109–1112. doi:10.1126/science.276.5315.1109.
[9]
C.L. Shen, R.M. Murphy, Solvent effects on self-assembly of beta-amyloid peptide, Biophys. J. 69 (1995) 640–651. doi:10.1016/S0006-3495(95)79940-4.
[10]
C.M. Dobson, B.E.P. Swoboda, M. Joniau, C. Weissman, The structural basis of protein folding and its links with human disease, in: C.M. Dobson, R.J. Ellis, A.R. Fersht (Eds.), Philos. Trans. R. Soc. B Biol. Sci., 2001: pp. 133–145. doi:10.1098/rstb.2000.0758.
[11]
C.L. Masters, R. Bateman, K. Blennow, C.C. Rowe, R.A. Sperling, J.L. Cummings, Alzheimer’s disease, Nat. Rev. Dis. Prim. 1 (2015) 15056. doi:10.1038/nrdp.2015.56.
[12]
F. Chiti, C.M. Dobson, Protein Misfolding, Functional Amyloid, and Human Disease, Annu. Rev. Biochem. 75 (2006) 333–366. doi:10.1146/annurev.biochem.75.101304.123901.
12
[13]
D.J. Selkoe, J. Hardy, The amyloid hypothesis of Alzheimer’s disease at 25 years, EMBO Mol. Med. 8 (2016) 595–608. doi:10.15252/emmm.201606210.
[14]
G.S.
Bloom,
Amyloid-β
and
Tau,
JAMA
Neurol.
71
(2014)
505.
doi:10.1001/jamaneurol.2013.5847. [15]
S. Giorgetti, C. Greco, P. Tortora, F.A. Aprile, Targeting amyloid aggregation: An overview of strategies and mechanisms, Int. J. Mol. Sci. 19 (2018). doi:10.3390/ijms19092677.
[16]
A. Baumketner, Electric field as a disaggregating agent for amyloid fibrils, J. Phys. Chem. B. 118 (2014) 14578–14589. doi:10.1021/jp509213f.
[17]
S. Ben Halima, S. Mishra, K.M.P. Raja, M. Willem, A. Baici, K. Simons, O. Brüstle, P. Koch, C. Haass, A. Caflisch, L. Rajendran, Specific Inhibition of β-Secretase Processing of the Alzheimer
Disease
Amyloid
Precursor
Protein,
Cell
Rep.
14
(2016)
2127–2141.
doi:10.1016/j.celrep.2016.01.076. [18]
T. Jonsson, J.K. Atwal, S. Steinberg, J. Snaedal, P. V. Jonsson, S. Bjornsson, H. Stefansson, P. Sulem, D. Gudbjartsson, J. Maloney, K. Hoyte, A. Gustafson, Y. Liu, Y. Lu, T. Bhangale, R.R. Graham, J. Huttenlocher, G. Bjornsdottir, O.A. Andreassen, E.G. Jönsson, A. Palotie, T.W. Behrens, O.T. Magnusson, A. Kong, U. Thorsteinsdottir, R.J. Watts, K. Stefansson, A mutation in APP protects against Alzheimer’s disease and age-related cognitive decline, Nature. 488 (2012) 96–99. doi:10.1038/nature11283.
[19]
K.G. Yiannopoulou, S.G. Papageorgiou, Current and future treatments for Alzheimer’s disease, Ther. Adv. Neurol. Disord. 6 (2013) 19–33. doi:10.1177/1756285612461679.
[20]
M.W. Beck, S.B. Oh, R.A. Kerr, H.J. Lee, S.H. Kim, S. Kim, M. Jang, B.T. Ruotolo, J.Y. Lee, M.H. Lim, A rationally designed small molecule for identifying an in vivo link between metalamyloid-β complexes and the pathogenesis of Alzheimer’s disease, Chem. Sci. 6 (2015) 1879–1886. doi:10.1039/c4sc03239j.
[21]
J.M. Orgogozo, S. Gilman, J.F. Dartigues, B. Laurent, M. Puel, L.C. Kirby, P. Jouanny, B. Dubois, L. Eisner, S. Flitman, B.F. Michel, M. Boada, A. Frank, C. Hock, Subacute meningoencephalitis in a subset of patients with AD after Aβ42 immunization, Neurology. 61 (2003) 46–54. doi:10.1212/01.WNL.0000073623.84147.A8.
[22]
E. Zenaro, G. Piacentino, G. Constantin, The blood-brain barrier in Alzheimer’s disease, Neurobiol. Dis. 107 (2017) 41–56. doi:10.1016/j.nbd.2016.07.007.
[23]
D.I. de Pomerai, B. Smith, A. Dawe, K. North, T. Smith, D.B. Archer, I.R. Duce, D. Jones, E.P.M. Candido, Microwave radiation can alter protein conformation without bulk heating, FEBS Lett. 543 (2003) 93–97. doi:10.1016/S0014-5793(03)00413-7.
[24]
G. Leinenga, J. Götz, Scanning ultrasound removes amyloid-β and restores memory in an Alzheimer’s
disease mouse model, Sci. Transl. Med.
7 (2015)
278ra33-278ra33.
13
doi:10.1126/scitranslmed.aaa2512. [25]
D. Lin, R. He, S. Li, Y. Xu, J. Wang, G. Wei, M. Ji, X. Yang, Highly Efficient Destruction of Amyloid-β Fibrils by Femtosecond Laser-Induced Nanoexplosion of Gold Nanorods, ACS Chem. Neurosci. 7 (2016) 1728–1736. doi:10.1021/acschemneuro.6b00244.
[26]
T.J. Measey, F. Gai, Light-Triggered Disassembly of Amyloid Fibrils, Langmuir. 28 (2012) 12588–12592. doi:10.1021/la302626d.
[27]
W. Lee, H. Jung, M. Son, H. Lee, T.J. Kwak, G. Lee, C.H. Kim, S.W. Lee, D.S. Yoon, Characterization of the regrowth behavior of amyloid-like fragmented fibrils decomposed by ultrasonic treatment, RSC Adv. 4 (2014) 56561–56566. doi:10.1039/C4RA08270B.
[28]
P. Marracino, F. Apollonio, M. Liberti, G. D’Inzeo, A. Amadei, Effect of high exogenous electric pulses on protein conformation: Myoglobin as a case study, J. Phys. Chem. B. 117 (2013) 2273–2279. doi:10.1021/jp309857b.
[29]
X. Wang, Y. Li, X. He, S. Chen, J.Z.H. Zhang, Effect of strong electric field on the conformational
integrity
of
insulin,
J.
Phys.
Chem.
A.
118
(2014)
8942–8952.
doi:10.1021/jp501051r. [30]
J. Saikia, G. Pandey, S. Sasidharan, F. Antony, H.B. Nemade, S. Kumar, N. Chaudhary, V. Ramakrishnan, Electric Field Disruption of Amyloid Aggregation: Potential Noninvasive Therapy for Alzheimer’s Disease, ACS Chem. Neurosci. (2019) acschemneuro.8b00490. doi:10.1021/acschemneuro.8b00490.
[31]
H. Alizadeh, J. Davoodi, H. Rafii-Tabar, Deconstruction of the human connexin 26 hemichannel due to an applied electric field; A molecular dynamics simulation study, J. Mol. Graph. Model. 73 (2017) 108–114. doi:10.1016/j.jmgm.2017.02.006.
[32]
Z. Jiang, L. You, W. Dou, T. Sun, P. Xu, Effects of an Electric Field on the Conformational Transition of the Protein: A Molecular Dynamics Simulation Study, Polymers (Basel). 11 (2019) 282. doi:10.3390/polym11020282.
[33]
Y. Lu, X.F. Shi, F.R. Salsbury, P. Derreumaux, Small static electric field strength promotes aggregation-prone
structures
in
amyloid-β(29-42),
J.
Chem.
Phys.
146
(2017).
doi:10.1063/1.4979866. [34]
Y. Lu, X.-F. Shi, F.R. Salsbury, P. Derreumaux, Influence of electric field on the amyloid- β (29-42) peptides embedded in a membrane bilayer, J. Chem. Phys. 148 (2018) 045105. doi:10.1063/1.5018459.
[35]
P. Marracino, D. Havelka, J. Průša, M. Liberti, J. Tuszynski, A.T. Ayoub, F. Apollonio, M. Cifra, Tubulin response to intense nanosecond-scale electric field in molecular dynamics simulation, Sci. Rep. 9 (2019) 10477. doi:10.1038/s41598-019-46636-4.
[36]
G.Y. Solomentsev, N.J. English, D.A. Mooney, Effects of external electromagnetic fields on the 14
conformational sampling of a short alanine peptide, J. Comput. Chem. 33 (2012) 917–923. doi:10.1002/jcc.22912. [37]
A. Amadei, P. Marracino, Theoretical-computational modelling of the electric field effects on protein unfolding thermodynamics, RSC Adv. 5 (2015) 96551–96561. doi:10.1039/c5ra15605j.
[38]
Y. Xie, C. Liao, J. Zhou, Effects of external electric fields on lysozyme adsorption by molecular dynamics simulations, Biophys. Chem. 179 (2013) 26–34. doi:10.1016/j.bpc.2013.05.002.
[39]
F. Toschi, F. Lugli, F. Biscarini, F. Zerbetto, Effects of Electric Field Stress on a β-Amyloid Peptide, J. Phys. Chem. B. 113 (2009) 369–376. doi:10.1021/jp807896g.
[40]
F. Lugli, F. Toschi, F. Biscarini, F. Zerbetto, Electric field effects on short fibrils of aβ amyloid peptides, J. Chem. Theory Comput. 6 (2010) 3516–3526. doi:10.1021/ct1001335.
[41]
N.K. Pandey, S. Mitra, M. Chakraborty, S. Ghosh, S. Sen, S. Dasgupta, S. DasGupta, Disruption of human serum albumin fibrils by a static electric field, J. Phys. D. Appl. Phys. 47 (2014). doi:10.1088/0022-3727/47/30/305401.
[42]
N.J. English, C.J. Waldron, Perspectives on external electric fields in molecular simulation: Progress, prospects and challenges, Phys. Chem. Chem. Phys. 17 (2015) 12407–12440. doi:10.1039/c5cp00629e.
[43]
N. Todorova, A. Bentvelzen, N.J. English, I. Yarovsky, Electromagnetic-field effects on structure and dynamics of amyloidogenic peptides, J. Chem. Phys. 144 (2016) 085101. doi:10.1063/1.4941108.
[44]
E.D. Kirson, Z. Gurvich, R. Schneiderman, E. Dekel, A. Itzhaki, Y. Wasserman, R. Schatzberger, Y. Palti, Disruption of Cancer Cell Replication by Alternating Electric Fields, Cancer Res. 64 (2004) 3288–3295. doi:10.1158/0008-5472.CAN-04-0083.
[45]
E.D. Kirson, V. Dbalý, F. Tovaryš, J. Vymazal, J.F. Soustiel, A. Itzhaki, D. Mordechovich, S. Steinberg-Shapira, Z. Gurvich, R. Schneiderman, Y. Wasserman, M. Salzberg, B. Ryffel, D. Goldsher, E. Dekel, Y. Palti, Alternating electric fields arrest cell proliferation in animal tumor models and human brain tumors, Proc. Natl. Acad. Sci. U. S. A. 104 (2007) 10152–10157. doi:10.1073/pnas.0702916104.
[46]
D. Barten, J. Mieke Kleijn, M.A. Cohen Stuart, Adsorption of a linear polyelectrolyte on a gold electrode, Phys. Chem. Chem. Phys. 5 (2003) 4258. doi:10.1039/b300229b.
[47]
G. Grasso, J.A. Tuszynski, U. Morbiducci, G. Licandro, A. Danani, M.A. Deriu, Thermodynamic and kinetic stability of the Josephin Domain closed arrangement: evidences from replica exchange molecular dynamics, Biol. Direct. 12 (2017) 2. doi:10.1186/s13062-016-0173-y.
[48]
G. Grasso, U. Morbiducci, D. Massai, J.A. Tuszynski, A. Danani, M.A. Deriu, Destabilizing the AXH Tetramer by Mutations: Mechanisms and Potential Antiaggregation Strategies, Biophys. J. 114 (2018) 323–330. doi:10.1016/j.bpj.2017.11.025. 15
[49]
G. Grasso, S. Muscat, M. Rebella, U. Morbiducci, A. Audenino, A. Danani, M.A. Deriu, Cell penetrating peptide modulation of membrane biomechanics by Molecular dynamics., J. Biomech. (2018). doi:10.1016/j.jbiomech.2018.03.036.
[50]
A. Basciu, G. Malloci, F. Pietrucci, A.M.J.J. Bonvin, A. V. Vargiu, Holo-like and Druggable Protein Conformations from Enhanced Sampling of Binding Pocket Volume and Shape, J. Chem. Inf. Model. 59 (2019) 1515–1528. doi:10.1021/acs.jcim.8b00730.
[51]
A. Atzori, G. Malloci, J.D. Prajapati, A. Basciu, A. Bosin, U. Kleinekathöfer, J. Dreier, A. V. Vargiu, P. Ruggerone, Molecular Interactions of Cephalosporins with the Deep Binding Pocket of
the
RND
Transporter
AcrB,
J.
Phys.
Chem.
B.
123
(2019)
4625–4635.
doi:10.1021/acs.jpcb.9b01351. [52]
G. Grasso, M. Rebella, S. Muscat, U. Morbiducci, J. Tuszynski, A. Danani, M. Deriu, Conformational Dynamics and Stability of U-Shaped and S-Shaped Amyloid β Assemblies, Int. J. Mol. Sci. 19 (2018) 571. doi:10.3390/ijms19020571.
[53]
G. Grasso, M. Rebella, U. Morbiducci, J.A. Tuszynski, A. Danani, M.A. Deriu, The Role of Structural Polymorphism in Driving the Mechanical Performance of the Alzheimer’s Beta Amyloid Fibrils, Front. Bioeng. Biotechnol. 7 (2019) 1–11. doi:10.3389/fbioe.2019.00083.
[54]
J. Razzokov, M. Yusupov, A. Bogaerts, Oxidation destabilizes toxic amyloid beta peptide aggregation, Sci. Rep. 9 (2019) 5476. doi:10.1038/s41598-019-41931-6.
[55]
L. Gremer, D. Schölzel, C. Schenk, E. Reinartz, J. Labahn, R.B.G. Ravelli, M. Tusche, C. Lopez-Iglesias, W. Hoyer, H. Heise, D. Willbold, G.F. Schröder, Fibril structure of amyloid-β(1– 42)
by
cryo–electron
microscopy,
Science
(80-.
).
358
(2017)
116–119.
doi:10.1126/science.aao2825. [56]
G. Bussi, D. Donadio, M. Parrinello, Canonical sampling through velocity rescaling, J. Chem. Phys. 126 (2007). doi:10.1063/1.2408420.
[57]
H.J.C. Berendsen, J.P.M. Postma, W.F. van Gunsteren,
a DiNola, J.R. Haak, Molecular
dynamics with coupling to an external bath, J. Chem. Phys. 81 (1984) 3684–3690. doi:10.1063/1.448118. [58]
M. Parrinello, A. Rahman, Polymorphic transitions in single crystals: A new molecular dynamics method, J. Appl. Phys. 52 (1981) 7182–7190. doi:10.1063/1.328693.
[59]
N.J. English, J.M.D. MacElroy, Hydrogen bonding and molecular mobility in liquid water in external
electromagnetic
fields,
J.
Chem.
Phys.
119
(2003)
11806–11813.
doi:10.1063/1.1624363. [60]
R. Reale, N.J. English, P. Marracino, M. Liberti, F. Apollonio, Dipolar response and hydrogenbond kinetics in liquid water in square-wave time-varying electric fields, Mol. Phys. 112 (2014) 1870–1878. doi:10.1080/00268976.2013.867081.
16
[61]
A. Budi, F.S. Legge, H. Treutlein, I. Yarovsky, Electric field effects on insulin chain-B conformation, J. Phys. Chem. B. 109 (2005) 22641–22648. doi:10.1021/jp052742q.
[62]
D. Xu, J.C. Phillips, K. Schulten, Protein response to external electric fields: Relaxation, hysteresis, and echo, J. Phys. Chem. 100 (1996) 12108–12121. doi:10.1021/jp960076a.
[63]
B. Hess, H. Bekker, H.J.C. Berendsen, J.G.E.M. Fraaije, LINCS: A linear constraint solver for molecular simulations, J. Comput. Chem. 18 (1997) 1463–1472. doi:10.1002/(SICI)1096987X(199709)18:12<1463::AID-JCC4>3.0.CO;2-H.
[64]
K. Lindorff-Larsen, S. Piana, K. Palmo, P. Maragakis, J.L. Klepeis, R.O. Dror, D.E. Shaw, Improved side-chain torsion potentials for the Amber ff99SB protein force field, Proteins Struct. Funct. Bioinforma. 78 (2010) 1950–1958. doi:10.1002/prot.22711.
[65]
W.L. Jorgensen, J. Chandrasekhar, J.D. Madura, R.W. Impey, M.L. Klein, Comparison of simple potential functions for simulating liquid water, J. Chem. Phys. 79 (1983) 926. doi:10.1063/1.445869.
[66]
Q. Zhang, Y. Han, L. Wu, Influence of electrostatic field on the adsorption of phenol on singlewalled carbon nanotubes: A study by molecular dynamics simulation, Chem. Eng. J. 363 (2019) 278–284. doi:10.1016/j.cej.2019.01.146.
[67]
J.A. Garate, A. Bernardin, Y. Escalona, C. Yanez, N.J. English, T. Perez-Acle, Orientational and Folding Thermodynamics via Electric Dipole Moment Restraining, J. Phys. Chem. B. 123 (2019) 2599–2608. doi:10.1021/acs.jpcb.8b09374.
[68]
M. Bernardi, P. Marracino, M. Liberti, J.-A. Gárate, C.J. Burnham, F. Apollonio, N.J. English, Controlling ionic conductivity through transprotein electropores in human aquaporin 4: a nonequilibrium molecular-dynamics study, Phys. Chem. Chem. Phys. 21 (2019) 3339–3346. doi:10.1039/C8CP06643D.
[69]
J.-A. Garate, N.J. English, J.M.D. MacElroy, Static and alternating electric field and distancedependent effects on carbon nanotube-assisted water self-diffusion across lipid membranes, J. Chem. Phys. 131 (2009) 114508. doi:10.1063/1.3227042.
[70]
Y. Xie, Y. Pan, R. Zhang, Y. Liang, Z. Li, Modulating protein behaviors on responsive surface by external electric fields: A molecular dynamics study, Appl. Surf. Sci. 326 (2015) 55–65. doi:10.1016/j.apsusc.2014.11.078.
[71]
B. Harish Vagadia, S.K. Vanga, A. Singh, V. Raghavan, Effects of thermal and electric fields on soybean trypsin inhibitor protein: A molecular modelling study, Innov. Food Sci. Emerg. Technol. 35 (2016) 9–20. doi:10.1016/j.ifset.2016.03.004.
[72]
Q.-L. Zhang, R.-Y. Yang, Fast transport of water molecules across carbon nanotubes induced by
static
electric
fields,
Chem.
Phys.
Lett.
644
(2016)
201–204.
doi:10.1016/j.cplett.2015.11.061.
17
[73]
J.J. Timmons, J. Preto, J.A. Tuszynski, E.T. Wong, Tubulin’s response to external electric fields
by
molecular
dynamics
simulations,
PLoS
One.
13
(2018)
e0202141.
doi:10.1371/journal.pone.0202141. [74]
Z. Jing, C. Liu, S.Y. Cheng, R. Qi, B.D. Walker, J.-P. Piquemal, P. Ren, Polarizable Force Fields for Biomolecular Simulations: Recent Advances and Applications, Annu. Rev. Biophys. 48 (2019) 371–394. doi:10.1146/annurev-biophys-070317-033349.
[75]
J.A. Lemkul, J. Huang, B. Roux, A.D. MacKerell, An Empirical Polarizable Force Field Based on the Classical Drude Oscillator Model: Development History and Recent Applications, Chem. Rev. 116 (2016) 4983–5013. doi:10.1021/acs.chemrev.5b00505.
[76]
J.W. Ponder, C. Wu, P. Ren, V.S. Pande, J.D. Chodera, M.J. Schnieders, I. Haque, D.L. Mobley, D.S. Lambrecht, R.A. DiStasio, M. Head-Gordon, G.N.I. Clark, M.E. Johnson, T. Head-Gordon, Current Status of the AMOEBA Polarizable Force Field, J. Phys. Chem. B. 114 (2010) 2549–2564. doi:10.1021/jp910674d.
[77]
F. Calvo, P. Dugourd, Folding of Gas-Phase Polyalanines in a Static Electric Field: Alignment, Deformations,
and
Polarization
Effects,
Biophys.
J.
95
(2008)
18–32.
doi:10.1529/biophysj.107.124685. [78]
J.A. Lemkul, B. Roux, D. Van Der Spoel, A.D. Mackerell, Implementation of extended Lagrangian dynamics in GROMACS for polarizable simulations using the classical Drude oscillator model, J. Comput. Chem. 36 (2015) 1473–1479. doi:10.1002/jcc.23937.
[79]
M.J. Abraham, T. Murtola, R. Schulz, S. Páll, J.C. Smith, B. Hess, E. Lindah, Gromacs: High performance
molecular
simulations
through
multi-level
parallelism
from
laptops
to
supercomputers, SoftwareX. 1–2 (2015) 19–25. doi:10.1016/j.softx.2015.06.001. [80]
W. Humphrey, A. Dalke, K. Schulten, VMD: Visual molecular dynamics, J. Mol. Graph. 14 (1996) 33–38. doi:10.1016/0263-7855(96)00018-5.
[81]
D.M.Á.V. Acosta, B.C. Vega, J.C. Basurto, L.G.F. Morales, M.C.R. Hernández, Recent advances by in silico and in vitro studies of amyloid-β 1-42 fibril depicted a S-shape conformation, Int. J. Mol. Sci. 19 (2018). doi:10.3390/ijms19082415.
[82]
G.G. Tartaglia, A. Cavalli, R. Pellarin, A. Caflisch, The role of aromaticity, exposed surface, and dipole moment in determining protein aggregation rates, Protein Sci. 13 (2004) 1939– 1941. doi:10.1110/ps.04663504.
[83]
M. Kouza, A. Banerji, A. Kolinski, I. Buhimschi, A. Kloczkowski, Role of Resultant Dipole Moment in Mechanical Dissociation of Biological Complexes, Molecules. 23 (2018) 1995. doi:10.3390/molecules23081995.
[84]
N.J. English, C.J. Waldron, Perspectives on external electric fields in molecular simulation: progress, prospects and challenges, Phys. Chem. Chem. Phys. 17 (2015) 12407–12440.
18
doi:10.1039/C5CP00629E. [85]
L.C. Serpell, P.E. Fraser, M. Sunde, [34] X-Ray fiber diffraction of amyloid fibrils, in: 1999: pp. 526–536. doi:10.1016/S0076-6879(99)09036-9.
[86]
Y. Zou, Z. Qian, Y. Chen, H. Qian, G. Wei, Q. Zhang, Norepinephrine Inhibits Alzheimer’s Amyloid-β Peptide Aggregation and Destabilizes Amyloid-β Protofibrils: A Molecular Dynamics Simulation
Study,
ACS
Chem.
Neurosci.
10
(2019)
1585–1594.
doi:10.1021/acschemneuro.8b00537. [87]
P. Ojeda-May, M.E. Garcia, Electric Field-Driven Disruption of a Native β-Sheet Protein Conformation and Generation of a Helix-Structure, Biophys. J. 99 (2010) 595–599. doi:10.1016/j.bpj.2010.04.040.
[88]
Y. Zheng, Q. Wang, X. Yang, W. Nie, L. Zou, X. Liu, K. Wang, Aptamer as a Tool for Investigating the Effects of Electric Field on Aβ 40 Monomer and Aggregates Using SingleMolecule
Force
Spectroscopy,
Anal.
Chem.
91
(2019)
1954–1961.
doi:10.1021/acs.analchem.8b04278. [89]
G. Pandey, S. Morla, H.B. Nemade, S. Kumar, V. Ramakrishnan, Modulation of aggregation with an electric field; Scientific roadmap for a potential non-invasive therapy against tauopathies, RSC Adv. 9 (2019) 4744–4750. doi:10.1039/c8ra09993f.
[90]
N. English, D. Mooney, Denaturation of hen egg white lysozyme in electromagnetic fields: A molecular dynamics study, 2007 NSTI Nanotechnol. Conf. Trade Show - NSTI Nanotech 2007, Tech. Proc. 1 (2007) 434–437. doi:10.1063/1.2515315.
[91]
M. Fändrich, S. Nyström, K.P.R. Nilsson, A. Böckmann, H. LeVine, P. Hammarström, Amyloid fibril polymorphism: a challenge for molecular imaging and therapy, J. Intern. Med. 283 (2018) 218–237. doi:10.1111/joim.12732.
19
Highlights
•
Systematic investigation of static electric field (EF) influence on Amyloid Beta 1-42 (Aβ142)
with molecular dynamics (MD) simulations.
•
The beta-sheet secondary structure is a key factor of Aβ stability.
•
The maximization of electric dipole moment is the driving force that lead to the amyloidbeta protein destabilization.
•
An external EF can be used as disaggregating agent of Aβ fibril.
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: