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Title: Glutathione-mediated binding of dibromoalkanes to DNA: specificity of rat glutathione-S-transferases and dibromoalkane structure.

Authors: Inskeep, P B; Guengerich, F P

Published In Carcinogenesis, (1984 Jun)

Abstract: 1,2-Dibromo-[1,2-14C]ethane was bound irreversibly to DNA when glutathione S-transferase or rat liver cytosolic components were added to incubations of calf thymus DNA and glutathione at 37 degrees C. There was no DNA binding of 1,2-dibromoethane when glutathione was absent or in incubations of DNA with microsomal proteins with or without NADPH, thus supporting the proposal that the major route of DNA binding by 1,2-dibromoethane occurs via conjugation to glutathione. In vitro binding of 1,2-dibromoethane occurred most effectively when the YaYc (or 'B') isozyme of glutathione S-transferase was included in incubations of DNA with 1,2-dibromoethane and glutathione. Other dihaloalkanes were incubated with DNA in the presence of glutathione S-transferase and [35S]glutathione. Of these, only 1,2-dibromo-3-chloropropane and tris-(2,3-dibromopropyl)-phosphate led to significant DNA binding of [35S]glutathione. 1,2-Dibromo-3-chloro-[1,3-14C]propane was bound to DNA when glutathione and glutathione S-transferase were present. However, even higher 1,2-dibromo-3-chloropropane binding to DNA occurred when cytosol or microsomes were included in incubations without glutathione. When glutathione was added to incubations containing cytosol and 1,2-dibromo-3-chloropropane, total DNA binding was decreased. Thus, the actual amount of DNA binding by dihaloethanes in vivo may be the result of a complicated balance among the opposing roles of glutathione conjugation in detoxicating and activating processes.

PubMed ID: 6373044 Exiting the NIEHS site

MeSH Terms: Animals; Carcinogens/metabolism*; Cattle; Cytosol/enzymology; DNA/metabolism*; Ethylene Dibromide/metabolism*; Glutathione Transferase/metabolism*; Glutathione/metabolism*; Hydrocarbons, Brominated/metabolism*; Liver/enzymology; Microsomes, Liver/metabolism; Organophosphates/metabolism; Propane/analogs & derivatives*; Propane/metabolism; Protein Binding; Proteins/metabolism; Rats; Structure-Activity Relationship; Thymus Gland

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