Isozyme selective arylation of cytosolic glutathione S-transferase by [14C]bromobenzene metabolites.
[14C]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 [14C]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. [14C]Bromobenzene metabolites were not bound to microsomal glutathione S-transferases. These data show that hepatic cytosolic glutathione S-transferases, especially glutathione S-transferases 4-4/5-5, 3-4, and 1-1 may act as trapping or scavenger proteins for reactive metabolites and that this effect is not associated with a loss of catalytic activity.
Aniya
Y
Y
Department of Pharmacology, University of Rochester, NY 14642.
McLenithan
J C
JC
Anders
M W
MW
D000818:Animals; D001665:Binding Sites; D001969:Bromobenzenes / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003600:Cytosol / Q000201:enzymology; D005982:Glutathione Transferase / Q000302:isolation & purification / Q000378:metabolism*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D046911:Macromolecular Substances; D008297:Male; D010634:Phenobarbital / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats
D001969:Bromobenzenes; D002250:Carbon Radioisotopes; D007527:Isoenzymes; D046911:Macromolecular Substances; D005982:Glutathione Transferase; D010634:Phenobarbital