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ON THE SPATIAL CORRELATION BETWEEN THE PROTEIN SURFACE AND THE ELECTRON TRANSFER CYCLE IN BACTERIAL PHOTOSYNTHETIC REACTION CENTERS
Author(s) -
Giangrande M.,
Kevan Larry
Publication year - 1981
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1981.tb05480.x
Subject(s) - moiety , photosynthetic reaction centre , chemistry , electron transfer , electron acceptor , nitroxide mediated radical polymerization , photochemistry , dimer , quinone , electron transport chain , molecule , stereochemistry , crystallography , polymerization , organic chemistry , radical polymerization , biochemistry , polymer
Abstract— n ‐Doxylstearic acids are shown to be electron acceptors in reaction centers from R. spheroides R‐26 mutant illuminated with 860 nm light. The electron accepting efficiency varies with n , thus with the location of the nitroxide moiety on the stearic acid chain, and is maximum for 12‐doxylstearic acid. In this molecule the nitroxide moiety is 1.4 nm from the polar carboxyl carbon based on molecular models. If the nitroxide moiety is located in or near the polar reaction center protein surface, the results suggest that the quinone‐iron complex, which is the ultimate electron acceptor from a bacterio‐chlorophyll dimer in the reaction center, is located ∼ 1.4 nm from the protein surface. The protein itself is estimated to have a diameter of 5.4 nm assuming spherical symmetry, so it is postulated that the quinone‐iron complex is located on one side of the protein.