title: A novel amphibian Pi-class glutathione transferase isoenzyme from Xenopus laevis: importance of phenylalanine 111 in the H-site.
abstract: Screening of a liver tumour cDNA library from Xenopus laevis resulted in the isolation of a full-length cDNA clone encoding a novel Pi-class amphibian glutathione transferase (GST) isoenzyme (designated as XlGSTP1-1). The gene encodes a protein of 212 amino acids with a calculated molecular mass of 24428 Da. The product of the gene has been overexpressed in Escherichia coli and characterized. XlGSTP1-1 has one of the highest specific activities towards 1-chloro-2,4-dinitrobenzene (1310 micromol/min per mg of protein) obtained with any GST. A notable feature of XlGSTP1-1 is the presence in the H-site of Phe(111) and Pro(208) in place of tyrosine and glycine residues respectively, present in other mammalian Pi-class GSTs. Site-directed mutagenesis indicate that Phe(111) is involved in substrate specificity of XlGSTP1-1. We provide evidence showing that XlGSTP1-1 is present only in the embryo and its expression might be associated with cellular proliferation.
authors.affiliation: Dipartimento di Scienze Biomediche, Università "G.D'Annunzio", Via dei Vestini, Chieti, CH 66100, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: De Luca
authors.forename: Bartolo
authors.initials: B
authors.lastname: Favaloro
authors.forename: Erminia
authors.initials: E
authors.lastname: Carletti
authors.forename: Paolo
authors.initials: P
authors.lastname: Sacchetta
authors.forename: Carmine
authors.initials: C
authors.lastname: Di Ilio
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004137:Dinitrochlorobenzene / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005998:Glycine / Q000737:chemistry; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D010649:Phenylalanine / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013379:Substrate Specificity; D014443:Tyrosine / Q000737:chemistry; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D004137:Dinitrochlorobenzene; D007527:Isoenzymes; D029867:Xenopus Proteins; D014443:Tyrosine; D010649:Phenylalanine; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D005998:Glycine