title: Intrinsic fluorescence quenching of glutathione transferase pi by glutathione binding.
abstract: The binding of the GSH to the GSH transferase pi quenches the protein intrinsic fluorescence more than the binding of GS-Me. The calculated dissociation constants are 38.6 microM and 90.9 microM for GSH and GS-Me, respectively. From the reported data it is evident that the binding of GSH to GSH transferase pi quenches the intrinsic fluorescence with two different mechanisms. The first one is a conformational change induced by the binding of the GSH and it is present also with the GS-Me binding. A second proposed mechanism is a contact quenching between the sulphydryl GSH group and a tryptophan residue. This suggests that at least one of the tryptophan residues is located near the GSH binding site.
authors.affiliation: Dipartimento di Biologia, Università Tor Vergata, Roma.
authors.forename: A M
authors.initials: AM
authors.lastname: Caccuri
authors.forename: A
authors.initials: A
authors.lastname: Aceto
authors.forename: N
authors.initials: N
authors.lastname: Rosato
authors.forename: C
authors.initials: C
authors.lastname: Di Ilio
authors.forename: F
authors.initials: F
authors.lastname: Piemonte
authors.forename: G
authors.initials: G
authors.lastname: Federici
mesh_terms: D002942:Circular Dichroism; D005260:Female; D005453:Fluorescence; D005470:Fluorometry; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D005982:Glutathione Transferase / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D011485:Protein Binding
chemical_list: D005982:Glutathione Transferase; D005978:Glutathione; C017514:S-methyl glutathione