Determination of 3-mercaptopyruvate-cysteine disulfide, a product of oxidative deamination of L-cystine by L-amino acid oxidase.

A rapid, sensitive and specific method of determining 3-mercaptopyruvate-cysteine disulfide is described. The method consists of the separation of the disulfide by means of a cation-exchange resin column, the reduction of the disulfide with dithiothreitol, and the determination of 3-mercaptopyruvate with lactate dehydrogenase. The method was applied to the determination of the disulfide which was formed from l-cystine through oxidative deamination by l-amino acid oxyidase from snake venom.