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The iron‐quinone electron‐acceptor complex of photosystem II
Author(s) -
Diner Bruce A.,
Petrouleas Vasili,
Wendoloski John J.
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb08753.x
Subject(s) - quinone , photosynthetic reaction centre , chemistry , electron transfer , purple bacteria , photosystem ii , crystallography , electron transport chain , photosystem i , electron acceptor , photosynthesis , stereochemistry , heme , cytochrome , molecule , p700 , cytochrome b6f complex , acceptor , photochemistry , biochemistry , physics , enzyme , condensed matter physics , organic chemistry
The iron quinone‐complex of the reaction centers of photosystem II and the purple non‐sulphur photosynthetic bacteria contains two quinones, Q A and Q B connected in series with respect to electron transfer, and separated by a non‐heme iron coordinated by amino acid residues. It is the site of inhibition of many of the common photosynthetic herbicides, which act by displacing Q B from the center. The complex is responsible for reducing Q B to Q B H 2 in two successive one‐electron photo acts. O B H 2 dissociates from the center, to be replaced by a new Q B molecule and reduces the following membrane‐bound electron‐transfer complex (cytochrome b6/for b/c1) . The energetic, kinetics and mechanism of complex function are reviewed here. Recent crystallographic, spectroscopic and molecular biological evidence has produced a considerable quantity of structural information on this complex. These data have given a less formal and more molecular view of how the complex functions. They have also revealed fundamental differences between the photo system II and bacterial complexes, particularly with respect to the coordination of the iron and its chemistry. The comparative anatomy of the complexes is reviewed and its implications for function discussed.