Purification of major basic glutathione transferase isoenzymes from rat liver by use of affinity chromatography and fast protein liquid chromatofocusing.

Seven major isoenzymes of glutathione transferase with isoelectric points ranging from pH 6.9 to 10 were isolated from rat liver cytosol. The purification procedure included affinity chromatography on immobilized S-hexylglutathione followed by high-performance liquid chromatofocusing. Characteristics, such as physical properties, reactions with antibodies, specific activities with various substrates, kinetic constants, and sensitivities to a set of inhibitors, are given for discrimination and identification of the different isoenzymes. The multiple forms of the enzyme correspond to glutathione transferases 1-1, 1-2, 2-2, 3-3, 3-4, and 4-4 in the recently introduced nomenclature [W.B. Jakoby et al. (1984) Biochem. Pharmacol. 33, 2539-2540]. A seventh form appears to be a heterodimeric protein composed of subunit 3 and an as yet unidentified subunit.