UNCOUPLING OF ELECTRON-TRANSPORT BY ANIONIC QUINONOID REDOX INDICATOR DYES

A considerable range of oxidation-reduction dyes was studied with reference to reactions with illuminated chloroplast (spinach) preparations. Experimental methods included dye-mediated H+- and H-transfer across liposome membranes, comparison of increase in the uncoupling properties with increase of substituting halogen atoms and effect of halogen substitution on distribution of anion between water and octanol. In the absence of halogen substitution a relatively high concentration of a dye is needed for significant uncoupling. Introduction of the sulphonic group -SO3Na abolishes the uncoupling effect even in presence of halogen substitution.