Clark AJ, Cotton NP, Jackson JB. The influence of the ionic conductance on the relation between electron transport and proton-motive force in intact cells of Rhodopseudomonas capsulata.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1983;
130:575-80. [PMID:
6297908 DOI:
10.1111/j.1432-1033.1983.tb07188.x]
[Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The dependence of membrane potential (delta psi) on the rate of respiration in darkened intact cell suspensions of Rhodopseudomonas capsulata was distinctly non-linear: severe inhibition of respiration with either rotenone or KCN led to only a small drop in delta psi. 2. In the presence of 0.3 microMs carbonylcyanide p-trifluoromethoxyphenylhydrazone [CF3OPhzC(CN)2] the dependence of delta psi on respiratory rate became linear. Consequently, and particularly at lower concentrations of CF3OPhzC(CN)2, there was a pronounced, synergistic depression of the respiratory delta psi with CF3OPhzC(CN)2 and either rotenone or KCN. 3. Antimycin A, at a concentration which strongly inhibited the photosynthetic electron transport chain, only slightly lowered the light-induced delta psi in anaerobic cell suspensions. Antimycin and CF3OPhzC(CN)2 synergistically lowered delta psi generated by illumination. 4. The light-induced delta psi in anaerobic cells was only about 1.5-times larger than the respiratory-induced delta psi in darkened cells. Nevertheless it required approximately 16-times more CF3OPhzC(CN)2 to collapse the photosynthetic delta psi than the respiratory delta psi. 5. These results are discussed with reference to the ionic current/delta psi relation described in [J.B. Jackson (1982) FEBS Lett. 139, 139-143]. The unifying feature is that the intrinsic conductance of the cell membrane is strongly dependent on delta psi but the conductance due to CF3OPhzC(CN)2 is independent of delta psi.
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