- Email: [email protected]
P-E2-20 Spectroscopy and structure of antenna complexes; differences and similarities of LH1 and LH2
E2 Structure and function of other photosynthetic complexes P-E2-17
P-E2-18 A ~~WTROSCtM”IC
CHARACTEI?U5WWN ‘Dept. of Physics and Astronomy, Vrije Universiteit. Amsterdam (NL), 2Max-Vohner-Institut. Technische Universittit Berlin (D)
Purpose: To characterizestructureand function of photosystem I core antenna pigments with lower energy than the primaty electron donor WOO.
Biological Sciences, Vrije Univ. Amsterdam (NL). ‘Botanisches Inst. III da Univ. Mtinchen (D)
Purpose: ln order to investigate the influence of pigment content on spectroscopicproperties. reconstituted LHCll complexeswith large variations in the Chla/ Chlb/ carotenoid ratios have been analysed. Methods: Monomeric LHCll was reconstituted from the apoprotein overexpmssedin Escherichia Coli. Pigments were extracted from chloroplast membranes. We have performed circular dichroism, fluorescenceemissionand excitation and triplet-singlet measurements. Results: Reconstituted LHCll with large variations in pigment composition showsstill significant singlet and triplet excitation transfer. Conclusions: When the pigment ratio and content of a reconstituted complex ate mom comparableto native LHCII. than the complex is more stableand the excitation transfer better.
Methods: Polarized fluorescenceline-narrowing spectroscopy,circular dichroismand siteselective absorbance-differencespectroscopyas a function of temperature from 4K to 293K. Results: Significant differencesin the amounts and eneraiesof long-wavelengthchloronhvlls in photosys?emI of v&ious cyan
P-E2-20
P-E2-19 LOW TEMi%RATUUESTARKSPECTROSCOPY ON TRIMER~CAND AGGREGATED LHC II COMPLEXES GRADINARU C.C., FRBSE R., VAN AMERONGEN VAN GRONDELLE R. Dept of Physics and Astronomy, Amsterdam (NL)
OF LHCII
REXONSTITUTED IklTH DIFFERENT PIGMENT RATIOS KLEIMA FJ,’ CALKOEN F,’ URBANUS ML,’ BORST HC,’ PBTBRMAN BlG,’ VAN GRONDELLE R,’ VAN Ah4ERONGENH, ’ HOBE S,’ PAULSEN H.2 ‘Depr of Physics and Astronomy and Inst. for Molecular
SPECTROSCOPY AND STRCTCTURE OF ANTENNA COMl%~WF’~ ENCES AND SIMILARITIES OF LHl
AND LH2
H..
KOOLHAAS MHC,’ VAN DER ZWAN G,’ VAN MOURIK F,1 VAN GRONDELLE R2 l F’ac. of Chemistry, sPac. ofPhysicsandAatronomy, Vrije Universiteit, Amsterdam (NL). ‘Purpose: Relating absorption and CD s&c&scopy of BChl dimers to their geometric structure. Methods: Analytical and numerical c&da-, tions on coupled N-level systems(N13, 5), includi diagonal disorder, and statistical analysis To spectroscopic data. Results: The non conservative nature of the QY band of the CD spectrum of the LHl sub strtuent B&Xl is a consequenceof the near coplanarity of the Q transiticn momenta and the vector connecting B e centers of the BCI-Il pair. This results in a relatively large contribution of (non-resonant) higher transitions to the CD spectrum. In general non-conservative CD spectra give severe limit&ions on the geometry of dimers. Conclusions: SpectroscopicallyLHI is a collection of BChl dimers. The relative orientation of the chromophores in LHl is different from the (known X-ray) structure in LH2.
Vrije Universiteit,
Purpose: Revealing of the band structure and calculation of some molecular pammetem such as changes in polatizability (Aa) and permamxtt dipole moment (4) upon excitation, for the Chls a. Chls b and the carotenoids of the LHC II antenna. MeUmdtttThc study of the induced elecuochromic changes in the steady-state abaotption at low tempemmn #7K), by using a high electric field (lMV/cm). To test the aggregation atstc we used the low temperature emission specwum.
Results.Thevaluesfor
Aa and At.t deduced from the fitting wem cornpad to thoseof the free pigmen& thus providing information about the excitonic coupling in the Chl Q, spectral region, and about the type of the carotenoids showing Stark signal.
Conclusions: The position and the relative amplitudes of the bands are significantly diffennt from the ones measured before ( Krawczyk S. et al. in B.B.A., 1143 (1993). 273-281) and that leads to a new interpretation of the different contributions in the Stark spectra of LHC II.
155
P-E2-18 A ~~WTROSCtM”IC
CHARACTEI?U5WWN ‘Dept. of Physics and Astronomy, Vrije Universiteit. Amsterdam (NL), 2Max-Vohner-Institut. Technische Universittit Berlin (D)
Purpose: To characterizestructureand function of photosystem I core antenna pigments with lower energy than the primaty electron donor WOO.
Biological Sciences, Vrije Univ. Amsterdam (NL). ‘Botanisches Inst. III da Univ. Mtinchen (D)
Purpose: ln order to investigate the influence of pigment content on spectroscopicproperties. reconstituted LHCll complexeswith large variations in the Chla/ Chlb/ carotenoid ratios have been analysed. Methods: Monomeric LHCll was reconstituted from the apoprotein overexpmssedin Escherichia Coli. Pigments were extracted from chloroplast membranes. We have performed circular dichroism, fluorescenceemissionand excitation and triplet-singlet measurements. Results: Reconstituted LHCll with large variations in pigment composition showsstill significant singlet and triplet excitation transfer. Conclusions: When the pigment ratio and content of a reconstituted complex ate mom comparableto native LHCII. than the complex is more stableand the excitation transfer better.
Methods: Polarized fluorescenceline-narrowing spectroscopy,circular dichroismand siteselective absorbance-differencespectroscopyas a function of temperature from 4K to 293K. Results: Significant differencesin the amounts and eneraiesof long-wavelengthchloronhvlls in photosys?emI of v&ious cyan
P-E2-20
P-E2-19 LOW TEMi%RATUUESTARKSPECTROSCOPY ON TRIMER~CAND AGGREGATED LHC II COMPLEXES GRADINARU C.C., FRBSE R., VAN AMERONGEN VAN GRONDELLE R. Dept of Physics and Astronomy, Amsterdam (NL)
OF LHCII
REXONSTITUTED IklTH DIFFERENT PIGMENT RATIOS KLEIMA FJ,’ CALKOEN F,’ URBANUS ML,’ BORST HC,’ PBTBRMAN BlG,’ VAN GRONDELLE R,’ VAN Ah4ERONGENH, ’ HOBE S,’ PAULSEN H.2 ‘Depr of Physics and Astronomy and Inst. for Molecular
SPECTROSCOPY AND STRCTCTURE OF ANTENNA COMl%~WF’~ ENCES AND SIMILARITIES OF LHl
AND LH2
H..
KOOLHAAS MHC,’ VAN DER ZWAN G,’ VAN MOURIK F,1 VAN GRONDELLE R2 l F’ac. of Chemistry, sPac. ofPhysicsandAatronomy, Vrije Universiteit, Amsterdam (NL). ‘Purpose: Relating absorption and CD s&c&scopy of BChl dimers to their geometric structure. Methods: Analytical and numerical c&da-, tions on coupled N-level systems(N13, 5), includi diagonal disorder, and statistical analysis To spectroscopic data. Results: The non conservative nature of the QY band of the CD spectrum of the LHl sub strtuent B&Xl is a consequenceof the near coplanarity of the Q transiticn momenta and the vector connecting B e centers of the BCI-Il pair. This results in a relatively large contribution of (non-resonant) higher transitions to the CD spectrum. In general non-conservative CD spectra give severe limit&ions on the geometry of dimers. Conclusions: SpectroscopicallyLHI is a collection of BChl dimers. The relative orientation of the chromophores in LHl is different from the (known X-ray) structure in LH2.
Vrije Universiteit,
Purpose: Revealing of the band structure and calculation of some molecular pammetem such as changes in polatizability (Aa) and permamxtt dipole moment (4) upon excitation, for the Chls a. Chls b and the carotenoids of the LHC II antenna. MeUmdtttThc study of the induced elecuochromic changes in the steady-state abaotption at low tempemmn #7K), by using a high electric field (lMV/cm). To test the aggregation atstc we used the low temperature emission specwum.
Results.Thevaluesfor
Aa and At.t deduced from the fitting wem cornpad to thoseof the free pigmen& thus providing information about the excitonic coupling in the Chl Q, spectral region, and about the type of the carotenoids showing Stark signal.
Conclusions: The position and the relative amplitudes of the bands are significantly diffennt from the ones measured before ( Krawczyk S. et al. in B.B.A., 1143 (1993). 273-281) and that leads to a new interpretation of the different contributions in the Stark spectra of LHC II.
155