S-Nitrosoglutathione as a substrate for γ-glutamyl transpeptidase

Neil Hogg, Ravinder Jit Singh, Eugene Konorev, Joy Joseph, B. Kalyanaraman

Research output: Contribution to journalArticle

116 Scopus citations

Abstract

S-Nitrosoglutathione (GSNO) has been used as a nitric oxide (.NO) donor compound and has also been postulated to be involved in the transport of .NO in vivo. In this study we have examined the possibility that GSNO is a substrate for γ-glutamyl transpeptidase (γ-GT), an enzyme that hydrolyses the γ-glutamyl moiety of glutathione to give glutamate and cysteinylglycine. γ-GT accelerated the decomposition of GSNO, forming S-nitrosocysteinylglycine (CG-SNO) by a mechanism inhibitable by the γ-GT inhibitors acivicin and S-methylglutathione. The K(m) of γ-GT for GSNO was found to be 28 μM. In the presence of contaminating transition metal ions, γ-GT accelerated the release of .NO from GSNO, as CG-SNO is more susceptible to transition metal ion-dependent decomposition than GSNO. However, in the presence of the transition metal ion chelator diethylenetriaminepentaacetic acid, neither GSNO nor CG-SNO decomposed to generate .NO. Neither S-methylglutathione nor acivicin affected the vasodilatory response to GSNO in an isolated perfused rat heart. However, rat kidney homogenate stimulated the decomposition of GSNO by an acivicin-inhibitable mechanism. It is likely therefore that γ-GT is involved in the decomposition of GSNO in the kidney but not in the heart.

Original languageEnglish (US)
Pages (from-to)477-481
Number of pages5
JournalBiochemical Journal
Volume323
Issue number2
DOIs
StatePublished - Apr 15 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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