Purification and characterization of a novel alpha-class glutathione transferase from human liver

Anna Pastore, Mario Lo Bello, Gabriella Aureli, Giorgio Federici, Giorgio Ricci, Carmine Di Ilio, Raffaele Petruzzelli

Research output: Contribution to journalArticle

Abstract

The importance of glutathione transferases (GST) as a major group of detoxification enzymes is well known. The human liver possesses these enzymes in high concentration and in a multiplicity of forms. We describe here a novel glutathione transferase isoenzyme isolated from liver using glutathione affinity chromatography, DEAE-sepharose and Mono-Q ion-exchange chromatography. The isoenzyme is a dimer of approximately 25 kDa with a blocked N-termini. Its kinetic and immunological properties indicate that it belongs to the alpha-class of GSTs. Its isoelectric point (8.0) is closely related to GST α (pI 7.8) and GST β (pI 8.2) reported previously. More than 70% of the amino-acid sequence of this isoenzyme has been determined by automated Edman degradation procedure. The results suggest that this isoenzyme (which we term GST 8.0) may be a heterodimer of two, closely related, novel alpha-class GST subunits. Comparisons between the amino acid sequences of these two novel alpha-class subunits with those of the other alpha-class GST subunits already known indicate changes in a number of different residues localized in the electrophilic binding site. Further studies are needed to establish whether such differences are due to allelic polymorphism of the enzyme or to the existence of additional genes for alpha-class GSTs in human liver. These results are consistent with previous data which suggest that a multitude of different GSTs, especially of alpha class, are present in the human liver providing this tissue with an efficient mechanism of protection against xenobiotic and endogenous compounds. Copyright (C) 1998 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)1235-1243
Number of pages9
JournalInternational Journal of Biochemistry and Cell Biology
Volume30
Issue number11
DOIs
Publication statusPublished - 1998

Keywords

  • Alpha-class
  • Glutathione S-transferase
  • Human liver
  • Isoelectric point
  • Isoenzyme

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology

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