Open AccessPhotoreactions of Cytochromes in Algal Chloroplasts
Author(s) -
BÖHME Herbert,
KUNERT KarlJosef
Publication year - 1980
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1980.tb06027.x
Subject(s) - cytochrome b6f complex , plastocyanin , plastoquinone , photosystem i , cytochrome , cytochrome f , photosystem ii , electron transport chain , chloroplast , chemistry , cytochrome b , p700 , photochemistry , light harvesting complexes of green plants , cytochrome c1 , photosystem , photosynthesis , cytochrome c , biochemistry , thylakoid , coenzyme q – cytochrome c reductase , mitochondrion , mitochondrial dna , gene , enzyme
Light‐induced cytochrome redox reactions were investigated with algal chloroplasts capable of high rates of electron transport coupled to phosphorylation. The electron‐donor pool preceding photosystem I consists of membrane‐bound cytochrome f ‐554.5 and a soluble cytochrome c ‐553; the latter replaces the function of plastocyanin of higher‐plant chloroplasts. Both cytochromes are reduced by photosystem II and oxidized by photosystem I. A site of energy conservation precedes these c ‐type cytochromes. The data obtained with respect to the function of b ‐type cytochromes are comparable to those obtained with higher‐plant chloroplasts. Cyclic electron transport is mediated by cytochrome b ‐563 in a photosystem‐I‐dependent reaction. In addition, cytochrome b ‐563 may be reduced by photosystem II, in accordance with recent findings with intact spinach chloroplasts. It therefore appears that cytochrome b ‐563 is a member of both cyclic and non‐cyclic electron transport. In contrast to higher‐plant chloroplasts, redox reactions of cytochrome b ‐559 are observable without any pretreatments. Cytochrome b ‐559, high‐potential, is reduced by photosystem II through plastoquinone. In the presence of carbonyl cyanide m ‐chlorophenylhydrazone a cytochrome b ‐559 oxidation by photosystem II is measured.