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Reduction of cytochrome b ‐561 through the antimycin‐sensitive site of the ubiquinol‐cytochrome c 2 oxidoreductase complex of Rhodopseudomonas sphaeroides
Author(s) -
Glaser Elzbieta G.,
Meinhardt Steven W.,
Crofts Antony R.
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)80629-8
Subject(s) - ubiquinol , cytochrome b , coenzyme q – cytochrome c reductase , chemistry , cytochrome , cytochrome c1 , antimycin a , oxidoreductase , cytochrome c , rhodobacter sphaeroides , stereochemistry , photochemistry , biochemistry , electron transport chain , mitochondrion , photosynthesis , enzyme , mitochondrial dna , gene
Cytochrome b ‐561 of the ubiquinol‐cytochrome c 2 oxidoreductase complex of Rhodopseudomonas sphaeroides is reduced after flash illumination in the presence of myxothiazol in an antimycin‐sensitive reaction. Flash‐induced reduction was observed over the redox range in which cytochrome b ‐561 and the Q‐pool are both oxidized before the flash. The extent of reduction increased with increasing pH, and was maximal at pH > 10.0 where the extent approached that observed in the presence of antimycin following a group of flashes. Reduction of cytochrome b ‐561 in the presence of myxothiazol showed a lag of ~ 1 ms after the flash, followed by reduction with ( t ~ 6 ms; by analogy with the similar kinetics of the quinol oxidase site, we suggest that the rate is determined by collision with the QH 2 produced in the pool on flash excitation.