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Proton uptake by the chloroplast cytochrome bf complex

Hope, AB; Rich, PR; (1989) Proton uptake by the chloroplast cytochrome bf complex. BBA - Bioenergetics , 975 (1) pp. 96-103. 10.1016/S0005-2728(89)80206-3.

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Abstract

The proton uptake, ΔHn+, associated with turnover of the quinone reduction site (here termed the Qn site - see abbreviations) of the chloroplast cytochrome bf complex has been kinetically resolved. It was approximately correlated with cytochrome f rereduction in a range of conditions. ΔHn+ was inhibited by the quinol oxidation site (here termed the Qp site - see abbreviations) inhibitors stigmateilin and DBMIB, but was unaffected by NQNO, an effector of the quinone reduction site (the Qn site), or by antimycin A. At external pH of 6 and 8, ΔHn+ was equivalent to about one proton per Photosystem I per flash, i.e., each turnover of the complex caused a proton uptake. At intermediate pH values on the first flashthis value was lower, but it rose to around 1 on subsequent flashes, provided that they were given sufficiently rapidly. Comparable measurements were made in the absence of nonactin so that a transmembrane potential difference was present during proton uptake. This potential, of the order of 30-50mV, had little effect on the extent of ΔHn+. © 1989 Elsevier Science Publishers B.V. (Biomedical Division).

Type: Article
Title: Proton uptake by the chloroplast cytochrome bf complex
DOI: 10.1016/S0005-2728(89)80206-3
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: http://discovery.ucl.ac.uk/id/eprint/10026558
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