title: Experimental conditions affecting functional comparison of highly active glutathione transferases.
abstract: Glutathione transferases (GSTs, EC 2.5.1.18) possess multiple functions and have potential applications in biotechnology. Direct evidence of underestimation of activity of human GST A3-3 and porcine GST A2-2 measured at submicromolar enzyme concentrations is reported here for the first time. The combination of time-dependent and enzyme concentration-dependent loss of activity and the choice of the organic solvent for substrates were found to cause irreproducibility of activity measurements of GSTs. These effects contribute to high variability of activity values of porcine GST A2-2 and human Alpha-class GSTs reported in the literature. Adsorption of GSTs to surfaces was found to be the main explanation of the observed phenomena. Several approaches to improved functional comparison of highly active GSTs are proposed.
authors.affiliation: Department of Biochemistry and Organic Chemistry, Uppsala University, SE-75123 Uppsala, Sweden.
authors.forename: Natalia
authors.initials: N
authors.lastname: Fedulova
authors.forename: Bengt
authors.initials: B
authors.lastname: Mannervik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019281:Dimerization; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D013552:Swine; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D011994:Recombinant Proteins; D012997:Solvents; D005982:Glutathione Transferase; C495975:glutathione S-transferase A3-3, human; C119995:glutathione S-transferase alpha