[Sulfite oxidation by Thiocapsa roseopersicina]

Extracts of the cells of Thiocapsa roseopersicina, strains BBS and SL, grown in the light in anaerobic conditions and in the dark in aerobic conditions oxidize sulphite in the presence of cytochrome c and AMP or in the absence of AMP. The rate of the oxidation, especially AMP-dependent, is higher in the cells cultivated in the dark on a mineral medium. The oxidation of sulphite, both in the absence and presence of AMP, is related to the membrane fraction and is inhibited by p-CMB while azide and atebrine inhibit mainly AMP-independent sulphite oxidation. Two enzymes are presumed to be involved in sulphite oxidation by Thiocapsa roseopersicina: APS-reductase and sulphite: cytochrome c-oxidoreductase.