Purification and Characterization of Acidic Glutathione-S-Transferase from Human Peripheral Blood Leukocyte

Abstract

An acidic isoenzyme of glutathione-S-transferase (Ee 2.5.1.18) has been purified to homogeneity from human peripheral leukocytes through a combination of ion-exchange, gel filtration and S-hexylglutathione-agarose affinity chromatography. The purified enzyme exhibited specific activity of 188 ,u mol· min-1 . mg- 1 toward l-chloro-2,4-dinitrobenzene. The molecular weight of the protein, as determined by gel filtration, was 48,000. Electrophoresis under denaturing condition revealed a single band of molecular weight about 24500. indicating the enzyme is composed of two subunits with approximately equal size. The enzyme had an isoelectric point of 4.6, and an apparent Km of 0.64 mM for l-chloro-2,4-dinitrobenzene and 0.21 mM for reduced glutathione.