title: Microsomal glutathione S-transferase A1-1 with glutathione peroxidase activity from sheep liver: molecular cloning, expression and characterization.
abstract: A 25 kDa subunit of glutathione S-transferase (GST) from sheep liver microsomes (microsomal GSTA1-1) with a significant selenium-independent glutathione peroxidase activity has been isolated and characterized. Several analytical criteria, including EDTA stripping, protease protection assay and extraction with alkaline Na(2)CO(3), indicate that the microsomal GSTA1-1 is associated with the inner microsomal membrane. The specific cDNA nucleotide sequence reveals that the enzyme is made up of 222 amino acid residues and shares approx. 73-83% sequence similarity to Alpha-class GSTs from different species. The molecular mass, as determined by electrospray mass ionization, is 25611.3 Da. The enzyme is distinct from the previously reported rat liver microsomal GST in both amino acid sequence and catalytic properties [Morgenstern, Guthenberg and DePierre (1982) Eur. J. Biochem. 128, 243-248]. The microsomal GSTA1-1 differs from the sheep liver cytosolic GSTs, reported previously from this laboratory, in its substrate specificity profile and molecular mass [Reddy, Burgess, Gong, Massaro and Tu (1983) Arch. Biochem. Biophys. 224, 87-101]. In addition to catalysing the conjugation of 4-hydroxynonenal with GSH, the enzyme also exhibits significant glutathione peroxidase activity towards physiologically relevant fatty acid hydroperoxides, such as linoleic and arachidonic acid hydroperoxides, as well as phosphatidylcholine hydroperoxide, but not with H(2)O(2). Thus the microsomal GSTA1-1 isoenzyme might have an important role in the protection of biological membranes against oxidative damage.
authors.affiliation: Department of Veterinary Science, 115 Henning Building, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Prabhu
authors.forename: P V
authors.initials: PV
authors.lastname: Reddy
authors.forename: E
authors.initials: E
authors.lastname: Gumpricht
authors.forename: G R
authors.initials: GR
authors.lastname: Hildenbrandt
authors.forename: R W
authors.initials: RW
authors.lastname: Scholz
authors.forename: L M
authors.initials: LM
authors.lastname: Sordillo
authors.forename: C C
authors.initials: CC
authors.lastname: Reddy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005033:Ethylmaleimide / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D019803:Glutathione Disulfide / Q000494:pharmacology; D005982:Glutathione Transferase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D015151:Immunoblotting; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D017421:Sequence Analysis; D012756:Sheep
chemical_list: D007527:Isoenzymes; D011994:Recombinant Proteins; C042431:S-ethyl glutathione; D005982:Glutathione Transferase; C119995:glutathione S-transferase alpha; D005978:Glutathione; D005033:Ethylmaleimide; C017514:S-methyl glutathione; D019803:Glutathione Disulfide