title: Characterization of porcine alpha-class glutathione transferase A1-1.
abstract: An alpha-class glutathione transferase (GST) has been cloned from pig gonads. In addition to two conservative point mutations our nucleotide sequence presents a frame shift resulting from a missing A as compared to a previously published porcine GST A1-1 sequence. The deduced C-terminal amino-acid segment of the protein differs between the two variants. Repeated sequencing of cDNA isolated from different tissues and animals ruled out the possibility of a cloning artifact, and the deduced amino acid sequence of our clone showed higher similarity to related mammalian GST sequences. Hereafter, we refer to our cloned enzyme as GST A1-1 and to the previously published enzyme as GST A1-1(∗). The study of the tissue distribution of the GSTA1 mRNA revealed high expression levels in many organs, in particular adipose tissue, liver, and pituitary gland. Porcine GST A1-1 was expressed in Escherichia coli and its kinetic properties were determined using alternative substrates. The catalytic activity in steroid isomerization reactions was at least 10-fold lower than the corresponding values for porcine GST A2-2, whereas the activity with 1-chloro-2,4-dinitrobenzene was approximately 8-fold higher. Differences in the H-site residues of mammalian Alpha-class GSTs may explain the catalytic divergence.
authors.affiliation: Department of Biochemistry and Organic Chemistry, Uppsala University, Biomedical Center, Box 576, SE-75123 Uppsala, Sweden.
authors.forename: Natalia
authors.initials: N
authors.lastname: Fedulova
authors.forename: Françoise
authors.initials: F
authors.lastname: Raffalli-Mathieu
authors.forename: Bengt
authors.initials: B
authors.lastname: Mannervik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D055162:Biocatalysis; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D013552:Swine
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; D005982:Glutathione Transferase; C119995:glutathione S-transferase alpha