title: In vitro binding of 3,4,5,6-tetrachloro-1,2-benzoquinone by rat liver glutathione S-transferases.
abstract: The in vitro interaction of 3,4,5,6-tetrachloro-1,2-benzoquinone (o-chloranil) with rat liver glutathione S-transferases (GST) was studied, using reduced glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB) as substrates. o-Chloranil inhibited the GST activity in crude extracts in a dose dependent manner, while 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone did not. Each of the GST isoenzymes was inhibited, albeit at different degrees. Kinetic studies never revealed competitive inhibition kinetics, with GSH nor CDNB as the variable substrate. Titration of remaining GSH in appropriate incubation mixtures indicated a minor spontaneous conjugation of o-chloranil with GSH, which was not enzymatically activated. It is concluded that o-chloranil interact with GST by direct binding to these proteins. This binding could have a protective function against o-chloranil.
mesh_terms: D000818:Animals; D002703:Chloranil / Q000031:analogs & derivatives / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D011485:Protein Binding; D011809:Quinones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007527:Isoenzymes; D011809:Quinones; D002703:Chloranil; D005982:Glutathione Transferase; D005978:Glutathione; C039499:2-chloranil