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Calibration and time resolution of lumenal pH‐transients in chromatophores of Rhodobacter capsulatus following a single turnover flash of light: Proton release by the cytochrome bc 1 ‐complex is strongly electrogenic
Author(s) -
Mulkidjanian Armen Y.,
Junge Wolfgang
Publication year - 1994
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(94)01031-5
Subject(s) - rhodobacter , chemistry , cytochrome , rhodobacter sphaeroides , proton , electron transport chain , photochemistry , analytical chemistry (journal) , chromatography , biochemistry , photosynthesis , mutant , enzyme , physics , quantum mechanics , gene
The flash‐induced proton release into the lumen of chromatophores from Rhodobacter capsulatus was studied with Neutral red as pH‐indicator. Calibration of the acidification jump after a single flash yielded a much larger figure, at least 0.8 units, than previously thought. A slow kinetic phase of proton release (85–90% of total) was sensitive to inhibitors of the cytochrome bc 1 ‐complex. Its half‐rise time, about 10 ms, was the same as the rise time of the electrogenic reaction in the cytochrome bc 1 ‐complex that was recorded by electrochromism of carotenoids. The oxidoreduction of the two b ‐hemes was significantly faster ( t ½ ≅ 3 ms). Thus the major electrogenic event in the cytochome bc 1 ‐complex is proton and not electron transfer.