Purification and characterization of S-phenacylglutathione reductase from rat liver.

An enzyme catalyzing the reduction of S-(2,4-dichlorophenacyl)glutathione to 2',4'-dichloroacetophenone was purified to apparent homogeneity by ion exchange, gel filtration, and hydroxylapatite chromatography from rat hepatic cytosol. The molecular weight was 30,000-37,000. The enzyme is distinct from the glutathione S-transferases, mercaptopyruvate sulfurtransferase, and glyoxalase I. Substrate specificity studies showed that S-phenacylglutathiones are the preferred first substrates and that several thiols (glutathione, mercaptoethanol, L-cysteine, or cysteamine) serve as reducing substrates. The enzyme serves to convert toxic alpha-haloketones, which react rapidly and nonenzymatically with glutathione, to nontoxic alkyl ketones.