A thiol-disulfide transhydrogenase from yeast.

An enzyme is described which, when coupled with glutathione reductase, catalyzes a thiol-disulfide interchange between glutathione and a number of disulfide substrates of low molecular weight. The most purified preparation is homogeneous on the basis of the disc gel electrophoresis test. From its behavior on a column of Sephadex G-75, the enzyme appears to have a molecular weight of about 15,000. At low substrate concentrations, the reaction rate is greater with L-cystine than with any of the other substances tested, including D-cystine, diacetyl-L-cystine, L-cystine diamide, L-cystinyldiglycine, L-homocystine, and /3-hydroxyethyl disulfide.