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P-A3-28 Unfolding of phosphoglycerate kinase by guanidinium chloride
A3 Structural dynamics P-A3-25 QUANTUM-CLASSSICAL MOLECULAR DYNAMICS (QCMD) OF ENZYMATIC PROCESSES BALA P.‘X’,GROCHOWSKI P.‘, LESYNG B.‘, MCCAMMON J.A.’
P-A3-26 HYDRODYNAMlIC MOBILTY OF Ca2+-ATPaseOF SARCOPLASMIC RETICULUM IN VISCOUS SOLVENTS T6RC)K Ml,2, JAKAB GYl, BERCZI A2, Dux Ll , HORVATH L I.2
‘KM, Warsaw University ,* Institute of Physics,Nicolas Copernicus University, Torun (FL), %JCSD,La Jolla (US.4
*Department of Biochemistry Szent-GyiQyi Albert Medical School, Szeged,and &stitute of Biophysics, Biological ResearchCentre, Szeged, Hungary
Purpose: A QCMD model is designed for simulations of proton and electrontransfer processesin molecular systems.The primary goal of this study is the elucidationof enzymaticreactions. Method: The dynamicsof key protons in an enzyme’s active site is describedby the time-dependent Schroedingerequation. The dynamicsof the remaininlng atoms are describedusing MD. The coupling between the quantum proton(s) and the classicalatoms is accomplishedvia HellmannFeynmanforces aswell as the time dependenceof the potential energy function in the Schroedinger equation. The function is computed using an approximate valencebond (AVB) method. Results: QCMIXAVB simulationsof a hydrolytic processcatalyzedby phospholipazeAZ, including quantum-dynamicaldissociationof a water molecule in the active site, will be presented. Conclusions: The QCMDlAVB model is a practical tool for studiesof enzymaticreactions, seee.g. Bala et al., J.Phys.Chem.,100,2535-2545(1996)
Purpose: The hydrodynamic mobility of transmembrane proteins can be varied by increasing the viscosityof aqueousphase provided a significant portion is extended to this phase.
P-A3-27 THE EFFECT OF A Ah&HiFIIILIC CQUNT#XIVP if?& MODEL LIPID MEMBRANE KUBICA K.
Methods: The rotational rate of Ca-AT&e of sarcoplasmicreticulum was studied by saturation transfer ESRspectroscopyafter covalent labelling of intramembranoussulfhydril groups with spin-labelledmaleimide. Results: The effective rotational correlation time increasedlinearly with viscosity in the caseof sucrose,whereas a nonlinear depence was observedin the caseof glycerol. Conclusions: A method has been introduced for the analysisof hydrodynamic data and a height of 6.9 nm hasbeen estimated for the extramembranouspart of Ca-ATPasefrom STESRspectralmeasurements.
P-A3-28 UNFC&LDWG OF P KINASE BY G C-S P,’ RECEVEUR V,’ DURAND D,’ DESMADIUL M.2
‘i
Dept. of Physics and Biophysics, Agricultural Univ. of Wroclaw (POLAND)
‘L.L.B., C.E.-Saclay,G&m-Yvette univ. Paris-sod,&say(F).
Pu se: It seemsthat the coupling constant J. in theT amiltonian used for computer simulattons onte Carlo method) should have the form of a I2’ ear function of chain length 01. The model with new valuesof J has been applied to investigatethe effect of amphiphilic counterions on lipid membranes. Methods: Monte Carlo simulation based on the 1O-statePi&s model . with the co constant krdCn x a (where a IS a value to * oulld) was
(F), ‘L.E.P.C.M.,
Purpose: Intemediate states have been often observed when proteins unfold. Then the protein maybeeitherpalwlyunfol&dordevoidof tertiary suuctum like the so-calledmolten globule. We wanted to check t&e points for yeast phosphoglyceratek&se (PGK). Methods: Far-UV CD spectroscopywas used to assess the amount of secondary structure at difkmt tfemtmmt (Gdm-Cl) condons. The radius of &on of the protein was in&red dtom small-aagle neutron scattaiag eq&mcwts. The same de&rated solventwas used k both cases. ResskThetrpluidonourvesginwbythetwo
Conclusions: We tentatiwly co@& Work sponsored by KBN, grant no 6 P203 003 07
46
that yeast
P-A3-26 HYDRODYNAMlIC MOBILTY OF Ca2+-ATPaseOF SARCOPLASMIC RETICULUM IN VISCOUS SOLVENTS T6RC)K Ml,2, JAKAB GYl, BERCZI A2, Dux Ll , HORVATH L I.2
‘KM, Warsaw University ,* Institute of Physics,Nicolas Copernicus University, Torun (FL), %JCSD,La Jolla (US.4
*Department of Biochemistry Szent-GyiQyi Albert Medical School, Szeged,and &stitute of Biophysics, Biological ResearchCentre, Szeged, Hungary
Purpose: A QCMD model is designed for simulations of proton and electrontransfer processesin molecular systems.The primary goal of this study is the elucidationof enzymaticreactions. Method: The dynamicsof key protons in an enzyme’s active site is describedby the time-dependent Schroedingerequation. The dynamicsof the remaininlng atoms are describedusing MD. The coupling between the quantum proton(s) and the classicalatoms is accomplishedvia HellmannFeynmanforces aswell as the time dependenceof the potential energy function in the Schroedinger equation. The function is computed using an approximate valencebond (AVB) method. Results: QCMIXAVB simulationsof a hydrolytic processcatalyzedby phospholipazeAZ, including quantum-dynamicaldissociationof a water molecule in the active site, will be presented. Conclusions: The QCMDlAVB model is a practical tool for studiesof enzymaticreactions, seee.g. Bala et al., J.Phys.Chem.,100,2535-2545(1996)
Purpose: The hydrodynamic mobility of transmembrane proteins can be varied by increasing the viscosityof aqueousphase provided a significant portion is extended to this phase.
P-A3-27 THE EFFECT OF A Ah&HiFIIILIC CQUNT#XIVP if?& MODEL LIPID MEMBRANE KUBICA K.
Methods: The rotational rate of Ca-AT&e of sarcoplasmicreticulum was studied by saturation transfer ESRspectroscopyafter covalent labelling of intramembranoussulfhydril groups with spin-labelledmaleimide. Results: The effective rotational correlation time increasedlinearly with viscosity in the caseof sucrose,whereas a nonlinear depence was observedin the caseof glycerol. Conclusions: A method has been introduced for the analysisof hydrodynamic data and a height of 6.9 nm hasbeen estimated for the extramembranouspart of Ca-ATPasefrom STESRspectralmeasurements.
P-A3-28 UNFC&LDWG OF P KINASE BY G C-S P,’ RECEVEUR V,’ DURAND D,’ DESMADIUL M.2
‘i
Dept. of Physics and Biophysics, Agricultural Univ. of Wroclaw (POLAND)
‘L.L.B., C.E.-Saclay,G&m-Yvette univ. Paris-sod,&say(F).
Pu se: It seemsthat the coupling constant J. in theT amiltonian used for computer simulattons onte Carlo method) should have the form of a I2’ ear function of chain length 01. The model with new valuesof J has been applied to investigatethe effect of amphiphilic counterions on lipid membranes. Methods: Monte Carlo simulation based on the 1O-statePi&s model . with the co constant krdCn x a (where a IS a value to * oulld) was
(F), ‘L.E.P.C.M.,
Purpose: Intemediate states have been often observed when proteins unfold. Then the protein maybeeitherpalwlyunfol&dordevoidof tertiary suuctum like the so-calledmolten globule. We wanted to check t&e points for yeast phosphoglyceratek&se (PGK). Methods: Far-UV CD spectroscopywas used to assess the amount of secondary structure at difkmt tfemtmmt (Gdm-Cl) condons. The radius of &on of the protein was in&red dtom small-aagle neutron scattaiag eq&mcwts. The same de&rated solventwas used k both cases. ResskThetrpluidonourvesginwbythetwo
Conclusions: We tentatiwly co@& Work sponsored by KBN, grant no 6 P203 003 07
46
that yeast