Abstract
Covalent chromatographically isolated bovine kidney sulfhydryl oxidase was found to catalyze the oxidation of cysteine and cysteine-containing substrates as determined by assaying with 5,5′-dithiobis (2-nitrobenzoate). Monitoring the time-course of substrate disappearance and product formation by means of high-pressure liquid choromatography revealed that such partially renal sulfhydryl oxidase preparations catalyze the direct oxidation of glycylglycyl- l-cysteine to its disulfide form with no other detectable metabolic products. Accordingly, Gly-Gly-Cys appears to be better suited for routine assays of sulfhydryl oxidse activity than is the traditionally employed substrate, glutathione, whose oxidation can be initiated by γ-glutamyltransferase-catalyzed cleavage of the γ-peptide bond, leading to falsely ‘positive’ assays in the absence of sulfhydryl oxidase per se.
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Schedule a callMore From: Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Enzymology
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