Conformational States of Human Placental Glutathione Transferase as Probed by Limited Proteolysis

Mario Lobello, Anna Pastore, raffaele Petruzzelli, Michael W. Parker, Matthew C.J. Wilce, Giorgio Federici, Giorgio Ricci

Research output: Contribution to journalArticleResearchpeer-review

30 Citations (Scopus)

Abstract

Limited proteolysis experiments have been carried out on human placental glutathione transferase in its different forms. The reduced enzyme, as well as the oxidized form and that inactivated with cystamine were all sensitive to 10 % (w/w) trypsin, under nondenaturing conditions. The proteolytic cleavage was accompanied by a concomitant loss of enzymatic activity. On the contrary, the presence of glutathione or glutathione conjugates strongly protected the reduced enzyme against inactivation and from the proteolytic attack. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and peptide sequence analysis showed that only the peptide bond between Lys 44 and Ala 45 was cleaved. Since Lys 44 has been demonstrated to be involved in the glutathione binding, it is suggested that the region surrounding this amino acid residue (α B helix) could be more exposed to the solvent, in the absence of glutathione. Crystallographic data also indicated that this region is flexible, supporting the idea that it may be involved in the observed conformational change upon glutathione binding.

Original languageEnglish
Pages (from-to)804-810
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume194
Issue number2
DOIs
Publication statusPublished - 30 Jul 1993
Externally publishedYes

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