THE RIESKE PROTEIN FROM PURPLE SULFUR BACTERIA IS AN EXTRINSIC PROTEIN

The mode of membrane attachment of the Rieske iron-sulfur protein from cytochrome bc(1) complex of Rhodospirillum rubrum has been studied us ing biochemical approaches. In contrast to cytochrome c(1) the bacteri al Rieske protein was extracted from chromatophores using chaotropic a gents (NaSCN, urea: guanidine), an alkaline pH and relatively low conc entration of Triton X-100. The results presented here lead to the conc lusion, that the Rieske protein from chromatophores is extrinsic and t hat their association with the rest of the complex involves hydrophobi c interactions.