Synthesis and characterization of the oxygen and desthio analogues of glutathione as dead-end inhibitors of glutathione S-transferase.
The oxygen analogue, gamma-L-Glu-L-SerGly (GOH) and desthio analogue, gamma-L-Glu-L-AlaGly (GH) have been synthesized by a simple three step procedure involving active ester coupling of N-t-BOC-alpha-(4-nitrophenyl)-L-glutamate to L-SerGly and L-AlaGly, respectively. The two peptides are excellent dead-end inhibitors of isozymes 3-3 and 4-4 of rat liver glutathione S-transferase. At low fixed concentrations of 1-chloro-2,4-dinitrobenzene (CDNB) GOH and GH are linear competitive inhibitors of isozyme 3-3 vs glutathione with KI values of 13.0 and 116 microM, respectively. Both peptides are non-competitive (mixed-type) inhibitors vs CDNB when glutathione is the fixed substrate. Similar results are obtained with both peptides and isozyme 4-4. The results rule out ordered or ping-pong kinetic mechanisms where the electrophile adds first.
D000818:Animals; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors*; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology; D009842:Oligopeptides / Q000494:pharmacology*; D051381:Rats
D004137:Dinitrochlorobenzene; D007527:Isoenzymes; D009842:Oligopeptides; C041021:norophthalamic acid; C045056:gamma-glutamyl-seryl-glycine; D005982:Glutathione Transferase; D005978:Glutathione