Abstract
Green sulfur bacteria grow phototrophically using sulfide as well as thiosulfate as electron donor. In this study, we purified thiosulfate-oxidizing multi enzyme from Chlorobium tepidum. Thiosulfate-oxidizing multi enzyme catalyze oxidation of thiosulfate and reduction of cytochrome c. Three fractions (Fraction I, II, III) which are involved in oxidization of thiosulfate were purified by ammonium sulfate fractionation, anion-exchange chromatography and cation-exchange chromatography. Fraction I contains heterodimer of SoxY and SoxZ, Fraction II contains monomer of SoxB, and Fraction III contains heterotrimer of SoxA, SoxX, and CT1020. For electron transfer from thiosulfate to cytochrome c554, all of three fractions were indispensable in reaction mixtures. We estimated the Vmax value is 15 µM Cyt c554 reduction/µM each factor/min and the Km is 0.24 mM.
