Changes in membrane ionic conductance, but not changes in slip, can account for the non‐linear dependence of the electrochemical proton gradient upon the electron‐transport rate in chromatophores
- 1 July 1984
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 142 (1), 193-198
- https://doi.org/10.1111/j.1432-1033.1984.tb08269.x
Abstract
Decrease in the rate of cyclic electron transport (JE) measured from the absorbance changes associated with reaction center bacteriochlorophyll led to a less than proportionate decrease in the membrane potential (1.psi.) [of Rhodopseudomonas capsulata] measured by electrochromism. In principle this result can be explained either by a 1.psi.-dependent slip in the H+/e- coupling ratio (nE) or by a 1.psi.-dependent change in the membrane ionic conductance. Simultaneous measurement of the membrane ionic current (JDIS) did not reveal any significant changes in the H+/e- ratio (JDIS/JE) and showed that conductance changes (JDIS/1.psi.) account quantitatively for the curved dependence of 1.psi. on JE. Simultaneous recordings of JDIS and the extravesicular pH from cresol-red absorbance changes, suggest that protons are the main current-carrying species across the chromatophore membrane at high values of 1.psi. in the presence and absence of FO-ATPase inhibitor. At reduced 1.psi. the flux of other ions outweighs the H+ current.This publication has 29 references indexed in Scilit:
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