title: The hepatic glutathione transferases of the male little skate, Raja erinacea.
abstract: Five cytosolic glutathione transferases were isolated from the liver of the male little skate, Raja erinacea, a marine elasmobranch. They were designated E-1 through E-5 in order of their elution from a DEAE-cellulose column with a 0 to 100 mM KCl gradient in 0.01 M Tris (pH 8.0). Each eluted peak of glutathione transferase activity, after concentration, was applied to an affinity column prepared by reaction of epoxy-activated Sepharose 6B with glutathione (GSH). Elution of the various glutathione transferases from this column with GSH resulted in the further purification of each enzyme; the major glutathione transferase, E-4 and E-1, were purified to apparent homogeneity by this procedure. Skate glutathione transferase E-4 is dimeric and the subunits are either very similar or identical in molecular weight (about 26 000 daltons). Enzymes E-2 through E-5 were acidic proteins (pI less than 7.0) and had high specific glutathione transferase activity (0.3--12 mumol/min/mg protein) with benzo[a]pyrene 4,5-oxide (BPO) as substrate, whereas the other enzyme (E-1) had low activity (0.01 mumol/min/mg) with BPO and a basic pI (greater than 9.5). Bilirubin and hematin, non-substrate ligands, bound tightly to homogeneous E-4, with dissociation constants in the micromolar range.
mesh_terms: D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism; D001663:Bilirubin / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D003600:Cytosol / Q000201:enzymology; D005399:Fishes / Q000378:metabolism*; D005982:Glutathione Transferase / Q000302:isolation & purification* / Q000378:metabolism; D006427:Hemin / Q000378:metabolism; D007525:Isoelectric Focusing; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D008297:Male; D008970:Molecular Weight; D011817:Rabbits; D051381:Rats; D013379:Substrate Specificity
chemical_list: D001580:Benzopyrenes; D046911:Macromolecular Substances; C006707:benzo(a)pyrene 4,5-epoxide; D006427:Hemin; D005982:Glutathione Transferase; D001663:Bilirubin