Purification by affinity chromatography of yeast glutathione reductase, the enzyme responsible for the NADPH-dependent reduction of the mixed disulfide of coenzyme A and glutathione.

Glutathione reductase (NAD(P)H : oxidised-glutathione oxidoreductase, EC 1.6.4.2) was purified from baker's yeast by a new procedure involving affinity chromatography on 2',5'-ADP-Sepharose 4B. The yield was 65% of essentially homogeneous enzyme. The activity was assayed with both glutathione disulfide (GSSG) and the mixed disulfide of coenzyme A and glutathione (CoAssg). The two disulfide substrates gave coinciding activity profiles and a constant ratio of the activities in different chromatographic and electrophoretic systems. No evidence was obtained for the existence of a reductase specific for CoASSG distinct from glutathione reductase. It is concluded that normal baker's yeast contains a single reductase active with both GSSG and CoASSG.