Amphibian and bacterial glutathione transferases

It was found that the pi class GST, indicated as bbGSTP1-1 which is continu ously expressed at high level during Bufo bufo embryo development, declines to a very low level in adult toad liver and kidney being replaced by a nov el pi class isoenzyme indicated as bbGSTP2-2. Unlike bbGSTP1-1, bbGSTP2-2 i s able to conjugate organic hydroperoxide, suggesting that the transition f rom aquatic to terrestrial life may cause a switch of the GST amphibian pat tern promoting the expression of a GST able to counteract with higher effic iency the toxic effect of reactive metabolites of oxidative metabolism. The prototype of a new class (Beta class, PmCSTB1-1), prevalently localized in the periplam-s, has been purified and characterised from Proteus mirabilis . This enzyme, which could be implicated in the binding of antibiotics, sho ws several characteristics which distinguish it from other GST classes: (i) it does not appear to utilise any N-terminal Tyr, Ser or Cys residues as w ell as the C-terminal residues His106 and Lys107 to activate glutathione; ( ii) it has a molecule of GSH covalently bound to Cys10. (C) 2001 Elsevier S cience Ireland Ltd. All rights reserved.