PMID: 4150022Feb 1, 1974

Formation of 5-oxoproline from glutathione in erythrocytes by the gamma-glutamyltranspeptidase-cyclotransferase pathway

Proceedings of the National Academy of Sciences of the United States of America
A G PalekarA Meister

Abstract

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 eryth...Continue Reading

References

Apr 9, 2015·Human & Experimental Toxicology·J D XuH Lu
Aug 19, 1976·The New England Journal of Medicine·E Beutler
Oct 29, 2010·International Journal of Alzheimer's Disease·Orest HurkoDaniel Crowther
Sep 5, 2015·BioMed Research International·Susumu KageyamaAkihiro Kawauchi
Jul 5, 2016·Chemical & Pharmaceutical Bulletin·Hiromi IiJun'ichi Uenishi
Sep 1, 1975·Klinische Wochenschrift·H C Benöhr, H D Waller
Mar 1, 1983·Veterinary Research Communications·J P BraunA G Rico
Apr 9, 2009·Chemistry & Biodiversity·Manjeet DeshmukhPatrick Sinko

Related Concepts

Gamma-glutamyl transferase
Pyroglutamate
Carbon Radioisotopes
Pedameth
Acyltransferase
Peptide synthase
Erythrocytes
Dipeptidases
Glycine, Sodium Hydrogen Carbonate
Plasma Membrane

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