title: Porcine class pi glutathione S-transferase: anionic ligand binding and conformational analysis.
abstract: The equilibrium binding of the non-substrate ligands 8-anilino-1-naphthalene sulfonate and bromosulfophthalein to porcine class pi glutathione S-transferase (pGSTP1-1) was studied using a variety of techniques (size-exclusion HPLC, steady-state fluorescence, second-derivative spectroscopy, and chemical modification of cysteines). Both ligands share the same binding site which has a highly hydrophobic surface. Occupation of the site inhibits catalytic function with glutathione and 1-chloro-2,4-dinitrobenzene in a non-competitive manner. Data obtained from different structural probes either located at strategic regions of pGSTP1-1 (Trp-28, Trp-38 and Cys-45) or distributed throughout the protein molecule (tyrosine residues) suggest that binding induces a microstructural change that impacts on the functional conformation of the active site.
authors.affiliation: Department of Biochemistry, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: P
authors.initials: P
authors.lastname: Bico
authors.forename: J
authors.initials: J
authors.lastname: Erhardt
authors.forename: W
authors.initials: W
authors.lastname: Kaplan
authors.forename: H
authors.initials: H
authors.lastname: Dirr
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D000838:Anions; D005982:Glutathione Transferase / Q000737:chemistry*; D007527:Isoenzymes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D011487:Protein Conformation; D013448:Sulfobromophthalein / Q000737:chemistry; D013552:Swine
chemical_list: D000817:Anilino Naphthalenesulfonates; D000838:Anions; D007527:Isoenzymes; D008024:Ligands; D013448:Sulfobromophthalein; C027132:1-anilino-8-naphthalenesulfonate; D005982:Glutathione Transferase