Interaction of stigmatellin and DNP-INT with the Rieske iron-sulfur center of the chloroplast cytochromeb6-fcomplex

Abstract

Stigmatellin and DNP-INT are effective inhibitors of the catalytic activity of the plastoquinol-plastocyanin oxidoreductase complex (cytochrome b₆-f complex). Both inhibitors alter the EPR spectrum of the Rieske iron-sulfur center but do not produce band-shifts of cytochrome b-563. The midpoint redox potential of the Rieske center is unaffected by either inhibitor, although both alter the DBMIB-induced g-value shifts of the Rieske center. The results are considered in terms of binding domains for inhibitors in the cytochrome b₆-f complex.