title: Theta, a new class of glutathione transferases purified from rat and man.
abstract: Glutathione transferases (GSTs) of a novel class, which it is proposed to term Theta, were purified from rat and human liver. Two, named GST 5-5 and GST 12-12, were obtained from the rat, and one, named GST theta, was from the human. Unlike other mammalian GSTs they lack activity towards 1-chloro-2,4-dinitrobenzene and are not retained by GSH affinity matrices. Only GST 5-5 retains full activity during purification, and its activities towards the substrates 1,2-epoxy-3-(p-nitrophenoxy)propane, p-nitrobenzyl chloride, p-nitrophenethyl bromide, cumene hydroperoxide, dichloromethane and DNA hydroperoxide are 185, 86, 67, 42, 11 and 0.03 mumol/min per mg of protein respectively. Earlier preparations of GST 5-5 or GST E were probably a mixture of GST 5-5 and GST 12-12, which was largely inactive, and may also have been contaminated by less than 1% with another GSH peroxidase of far greater activity. Partial analysis of primary structure shows that subunits 5, 12 and theta are related to each other, particularly at the N-terminus, where 25 of 27 residues are identical, but have little relationship to the Alpha, Mu and Pi classes of mammalian GSTs. They do, however, show some relatedness to subunit I of Drosophila melanogaster [Toung, Hsieh & Tu (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 31-35] and the dichloromethane dehalogenase of Methylobacterium DM4 [La Roche & Leisinger (1990) J. Bacteriol, 172, 164-171].
authors.affiliation: University College and Middlesex School of Medicine, Department of Biochemistry, London, U.K.
authors.forename: D J
authors.initials: DJ
authors.lastname: Meyer
authors.forename: B
authors.initials: B
authors.lastname: Coles
authors.forename: S E
authors.initials: SE
authors.lastname: Pemble
authors.forename: K S
authors.initials: KS
authors.lastname: Gilmore
authors.forename: G M
authors.initials: GM
authors.lastname: Fraser
authors.forename: B
authors.initials: B
authors.lastname: Ketterer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002845:Chromatography; D002846:Chromatography, Affinity; D003600:Cytosol / Q000201:enzymology; D017886:Durapatite; D005982:Glutathione Transferase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D006882:Hydroxyapatites; D007527:Isoenzymes / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D008297:Male; D008969:Molecular Sequence Data; D051381:Rats; D011919:Rats, Inbred Strains; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity
chemical_list: D006882:Hydroxyapatites; D007527:Isoenzymes; D046911:Macromolecular Substances; D017886:Durapatite; D005982:Glutathione Transferase