Isolation and characterization of an anionic glutathione S-transferase from rat liver cytosol

An anionic glutathione S-transferase representing approximately 20% of the total glutathione S-transferase protein and 10% of the total transferase activity toward 1-chloro 2,4-dinitrobenzene has been purified to homogeneity from the 105,000 x g supernatant of rat liver homogenate. The SDS gel electrophoretic data on subunit composition revealed that the anionic isozyme is composed of two subunits with an identical Mr of 26,000. The Km values for 1-chloro 2,4-dinitrobenzene and reduced glutathione were determined to be 0.94 mM and 0.23 mM respectively. A significant amount of glutathione peroxidase activity toward cumene hydroperoxide is associated with the new isozyme.