title: Substrate specificity of rat liver glutathione S-transferase isoenzymes for a series of glutathione analogues, modified at the gamma-glutamyl moiety.
abstract: The substrate specificity of purified rat liver glutathione S-transferases (GSTs) for a series of gamma-glutamyl-modified GSH analogues was investigated. GST isoenzyme 3-3 catalysed the conjugation of 1-chloro-2,4-dinitrobenzene with six out of the nine analogues. alpha-L-Glu-L-Cys-Gly and alpha-D-Glu-L-Cys-Gly showed catalytic efficiencies of 40% and 130% that of GSH respectively. The GSH analogue with an alpha-D-glutamyl moiety appeared to be a highly isoenzyme-3-3-specific co-substrate: kcat./Km with GST isoenzyme 4-4 was only about 5% that with GST isoenzyme 3-3, and no enzymic activity was detectable with GST isoenzymes 1-1 and 2-2. GST isoenzyme 4-4 showed some resemblance to GST 3-3: five out of nine co-substrate analogues were accepted by this second isoenzyme of the Mu multigene family. Isoenzymes 1-1 and 2-2, of the Alpha multigene family, accepted only two alternative co-substrates, which indicates that their GSH-binding site is much more specific.
authors.affiliation: Department of Organic Chemistry, University of Leiden, The Netherlands.
authors.forename: A E
authors.initials: AE
authors.lastname: Adang
authors.forename: J
authors.initials: J
authors.lastname: Brussee
authors.forename: D J
authors.initials: DJ
authors.lastname: Meyer
authors.forename: B
authors.initials: B
authors.lastname: Coles
authors.forename: B
authors.initials: B
authors.lastname: Ketterer
authors.forename: A
authors.initials: A
authors.lastname: van der Gen
authors.forename: G J
authors.initials: GJ
authors.lastname: Mulder
mesh_terms: D000818:Animals; D001665:Binding Sites; D005971:Glutamates; D018698:Glutamic Acid; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D051381:Rats; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D005971:Glutamates; D007527:Isoenzymes; D018698:Glutamic Acid; D005982:Glutathione Transferase; D005978:Glutathione