Characterization of a class alpha glutathione- S-transferase with glutathione peroxidase activity in human liver microsomes

• Published in: Archives of biochemistry and biophysics 2004-04, Vol.424 (1), p.72-80
• Main Authors: Sandeep Prabhu, K, Reddy, Padala V, Jones, Emily C, Liken, Andrew D, Channa Reddy, C
• Format: Article
• Language: English
• Subjects: Aldehydes - metabolism; Amino Acid Sequence; Animals; Benzene Derivatives - metabolism; Cell Line, Tumor; Dinitrochlorobenzene - metabolism; Dogs; Fatty acid hydroperoxides; Free Radicals - metabolism; Gene Expression - drug effects; Glutathione Peroxidase - metabolism; Glutathione Transferase - classification; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Humans; Hydrogen Peroxide - metabolism; Isoenzymes - classification; Isoenzymes - genetics; Isoenzymes - metabolism; Lactate Dehydrogenases - metabolism; Lipid Peroxides - chemistry; Lipid Peroxides - metabolism; MicrosomalGST-A; Microsomes, Liver - enzymology; NonSe-GPX; Oxidants - chemistry; Oxidants - pharmacology; Oxidative stress; Peroxidative damage; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sheep; Substrate Specificity; U937 Cells
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2004.02.002

A 25.5 kDa class alpha glutathione S-transferase (GST) designated as microsomal Ya-GST or M-GSTA has been purified to electrophoretic homogeneity from human liver microsomes. Limited proteolysis, gel filtration chromatography followed by EDTA, and alkaline Na 2CO 3 treatments of microsomes indicate that the M-GSTA is intrinsic to the microsomes. Western immunoblot analysis revealed that human liver M-GSTA and the previously reported 17-kDa microsomal GST (FEBS Lett. 315 (1993) 77) did not have immunological cross reactivity. The enzyme showed conjugation activity towards substrates like 1-chloro-2,4-nitrobenzene (CDNB) and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and 4-hydroxy-2-nonenal (4-HNE), a genotoxic α,β-unsaturated aldehyde product of lipid peroxidation. In addition, the M-GSTA exhibited significant glutathione peroxidase activity towards physiologically relevant fatty acid hydroperoxides as well as phosphatidylcholine hydroperoxide, but not with H 2O 2. C-terminal amino acid sequence analysis revealed a high homology with the human liver cytosolic GST-A1 and A3 isozymes. Western immunoblot analyses of the microsomes prepared from human hepatoblastoma (HepG2) showed that the expression of this M-GSTA was induced upon treatment with such prooxidants as H 2O 2, suggesting that it may play an important role in the protection of cellular membranes from peroxidative damage.