Isozyme selective arylation of cytosolic glutathione S-transferase by ( super(14)C)bromobenzene metabolites

( super(14)C)Bromobenzene was incubated with NADPH-fortified liver homogenates from phenobarbital-treated rats, after which the glutathione S-transferases were isolated from the incubation mixture. Glutathione S-transferase activity, with 1-chloro-2-4-dinitrobenzene as the substrate, in the homogenate was unchanged after incubation with bromobenzene. Radioactivity derived from the ( super(14)C)bromobenzene remained associated with the cytosolic glutathione s-transferases after DE52 and Sephadex G-100 chromatography. Further purification of the cytosolic glutathione S-transferase by CM52 and hydroxylapatite chromatography showed that bromobenzene metabolites were bound to fractions containing glutathione S-transferase subunits 4, 5, and 1. The primary site of arylation appeared to be subunit 1, as indicated by autoradiography and hydroxylapatite chromatography. ( super(14)C)Bromobenzene metabolites were not bound to microsomal glutathione S-transferases.