Formation of 5 oxoproline from glutathione in erythrocytes by the γ glutamyltranspeptidase cyclotransferase pathway Academic Article uri icon


MeSH Major

  • Acyltransferases
  • Erythrocytes
  • gamma-Glutamyltransferase


  • gamma-Glutamyltranspeptidase activity was demonstrated in the membrane fraction of rabbit erythrocytes. The activity observed (with glutathione and various amino-acid acceptors) was similar in magnitude to that of the gamma-glutamylcyclotransferase and gamma-glutamylcysteine synthetase activities found in the soluble fraction of the cell. No transpeptidase activity was observed with either gamma-glutamyl p-nitroanilide or oxidized glutathione in contrast to the rabbit-kidney enzyme for which these compounds and glutathione serve as substrates. Erythrocyte suspensions and hemolysates formed 5-oxoproline (pyroglutamate; pyrrolidone carboxylate); the rate of 5-oxoproline formation from glutathione by hemolysates was increased by addition of methionine. The findings indicate that 5-oxoproline is an end-product of glutathione metabolism in erythrocytes, and that 5-oxoproline passes out of the erythrocyte and is metabolized in other tissues. The observed rate of 5-oxoproline formation is consistent with the conclusion that the gamma-glutamyltranspeptidase-cyclotransferase pathway, together with the synthesis of glutathione from glycine, cysteine, and glutamate, account for a large fraction of the observed amino-acid turnover of erythrocyte glutathione.

publication date

  • January 1974



  • Academic Article



  • eng

PubMed Central ID

  • PMC387989

PubMed ID

  • 4150022

Additional Document Info

start page

  • 293

end page

  • 7


  • 71


  • 2