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Flash-induced electrogenic events in the photosynthetic reaction center and bc1- complexes of Rhodobacter sphaeroides chromatophoresстатья
Информация о цитировании статьи получена из
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Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Drachev L.A., Kaurov B.S., Mulkidjanian A.Ya, Mamedov M.D., Semenov A.Yu, Shinkarev V.P., Skulachev V.P., Verkhovsky M.I.
- Журнал: Biochimica et Biophysica Acta - Bioenergetics
- Том: 973
- Год издания: 1989
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 189
- Последняя страница: 197
- DOI: 10.1016/S0005-2728(89)80421-9
- Аннотация: Electrogenic events in Rb. Sphaeroides chromatophores have been studied (i) electrometrically in the chromatophore/phospholipid-impregnated collodion film system and (ii) spectrophotometrically by measuring the electrochromic spectral shift of carotenoids. Under the conditions when the bc1 complex and ubiquinone pool were oxidized at pH 7.5, the second flashwas shown to give rise to at least two additional electrogenic phases of τ values approx. 0.2 and approx. 20 ms, which were not induced by the first flash. The fast phase was resistant to the inhibitors of the bc1 complex, antimycin A and myxothiazol. It seems to be due to the protonation of reduced QB in the RC complex. The slow phase was partly inhibited by antimycin A and completely by subsequent addition of myxothiazol. The antimycin-sensitive constituent of the slow phase was τ ≈ 40 ms and its rise was non-exponential. The antimycin-insensitive, myxothiazol-sensitive constituent was τ ≈ 7 ms. A comparison of (i) the kinetics of cytochrome bhredox conversion induced by the first and second flashes and (ii) the electrogenic reactions sensitive to the Q-cycle inhibitors suggests that the myxothiazol-sensitive electrogenic phase is associated with the reduction of cytochrome bh(b-561). The antimycin-sensitive electrogenic phase apparently results from the protonation of reduced Q in the quinone-reducing center of the bct complex. Reduction of ubiquinone to ubisemiquinone by bh seems to be electrically silent, since there is no electrogenic phase to follow the kinetics of this process. Myxothiazol addedin the absence of antimycin A induced a negative electrogenic phase with an opposite polarity (τ ≈ 2.5 ms) after the second flash. This phase, completely abolished by the addition of antimycin A, is assumed to be due to the electrogenic deprotonation of the RC-reduced QH2 which combines with center C in the bc1 complex. The data obtained by the electrometric and spectrophotometric methods appear to be very similar, though the electrometric method is more sensitive because of the much higher signal-to-noise ratio.
- Добавил в систему: Мамедов Махир Джафар оглы