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Magnetic Resonance and Molecular Orbital Studies of the Primary Donor Cation Radical P +. 960 in the Photosynthetic Bacterium Rhodopseudomonas viridis
Author(s) -
Plato Martin,
Lubitz Wolfgang,
Lendzian Friedhelm,
Möbius Klaus
Publication year - 1988
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198800020
Subject(s) - chemistry , bacteriochlorophyll , photosynthetic reaction centre , unpaired electron , electron paramagnetic resonance , hyperfine structure , dimer , radical ion , electron transfer , crystallography , molecule , molecular orbital , electron donor , photochemistry , nuclear magnetic resonance , photosynthesis , atomic physics , ion , catalysis , biochemistry , physics , organic chemistry
The light‐induced radical cation of the primary electron donor, P +. 960 , in photosynthetic reaction centers (RCs) from Rhodopseudomonas viridis has been investigated by various magnetic resonance techniques (ESR, ENDOR, TRIPLE). Comparison of the measured hyperfine couplings with those of the cation radical of monomeric bacteriochlorophyll b (BChl b ) and with RHF‐INDO/SP molecular orbital calculations, performed on P +. 960 using coordinates of an X‐ray structure analysis, consistently show an asymmetric distribution of the unpaired electron over the two BChl b molecules which constitute P 960 . The derived spin density ratio is 2.8 in favor of the dimer half bound to the L protein subunit. The possible relevance of this result for the primary electron transfer step in the RC is briefly discussed.