Enzymes involved in the metabolism of thiosulfate by Thiobacillus thioparus. II. Properties of adenosine-5′-phosphosulfate reductase

1 March 1970

journal article
Published by Canadian Science Publishing in Canadian Journal of Biochemistry

Vol. 48 (3) , 344-354
https://doi.org/10.1139/o70-057

Abstract

Adenosine-5′-phosphosulfate (APS) reductase was purified from Thiobacillus thioparus extracts 25- to 46-fold and the properties were studied. The molecular weight was 170 000 and the enzyme had 1 mole of FAD, 8–10 moles of iron, and 4–5 moles of labile sulfide. Cytochrome c as well as ferricyanide served as the electron acceptor. The pH optimum shifted from 7.4 to 9.5 when cytochrome c was used instead of ferricyanide. The K_m values for sulfite and AMP were reduced from 2.5 mM and 100 μM to 17 μM and 2.5 μM, respectively, with cytochrome c as electron acceptor. Properties of the T. thioparus enzyme were compared to those of APS reductase isolated from Thiobacillus denitrificans and Desulfovibrio desulfuricans.

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