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.
A novel amphibian Pi-class glutathione transferase isoenzyme from Xenopus laevis: importance of phenylalanine 111 in the H-site
DE LUCA, Antonella;FAVALORO, Bartolo;CARLETTI, ERMINIA;SACCHETTA, Paolo;DI ILIO, Carmine
2003-01-01
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.File | Dimensione | Formato | |
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2003_BJ_ A novel amphibian Pi-class glutathione transferase isoenzyme from Xenopus laevis importance of phenylalanine 111 in the H site .PDF
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