Redox regulation of mammalian 3-mercaptopyruvate sulfurtransferase

Methods in Enzymology
Noriyuki NagaharaHidenori Suzuki

Abstract

A cystine-catabolizing enzyme, 3-mercaptopyruvate sulfurtransferase catalyzes the trans-sulfuration reaction of mercaptopyruvate or thiosulfate to thiol-containing compounds or cyanide. During the catalytic process, persulfide is formed at the catalytic site cysteine residue and a sulfur-acceptor substrate donates the outer sulfur of the persulfide to form a new persulfide molecule. Subsequently, the molecule can be reduced by thioredoxin to form hydrogen sulfide. The enzyme is regulated by redox changes via two redox-sensing molecular switches consisting redox-sensitive cysteine residues. One switch is the catalytic cysteine in itself, which is oxidized to form a cysteine-sulfenate resulting in inhibition of catalytic activity. The sulfenate can be reduced by thioredoxin resulting in restoration of the activity. The redox potential of sulfenate is lower than that of glutathione and greater than that of thioredoxin. The other switch involves cysteine residues positioned on the surface of the enzyme. The oxidation the intermolecular disulfide linkage at these cysteine residues, leading to dimer formation, inhibits enzyme activity. On the other hand, reduction-associated monomer formation increases catalytic activity. Thioredoxin...Continue Reading

Citations

Sep 12, 2018·Bioscience, Biotechnology, and Biochemistry·Motoko MaekawaTakeo Yoshikawa
Sep 5, 2020·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Ana HipólitoJacinta Serpa
Oct 16, 2020·Biological Chemistry·Brandán Pedre, Tobias P Dick
Dec 19, 2017·Biochemical Pharmacology·Kenneth R Olson

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