S NITROSOGLUTATHIONE AS SUBSTRATE FOR GAMMA GLUTAMYL TRANSPEPTIDASE

S-亚硝基谷胱甘肽（GSNO）已被用作一氧化氮供体 化合物，也被假定参与运输 体内一氧化氮的含量 在这项研究中，我们研究了 GSNO是γ-谷氨酰转肽酶底物的可能性 （γ-GT），一种水解γ-谷氨酰部分的酶， 谷胱甘肽，得到谷氨酸和半胱氨酰甘氨酸。 γ-GT 加速了GSNO的分解， S-亚硝基半胱氨酰甘氨酸（CG-SNO）通过一种可由 γ-GT抑制剂阿西维辛和S-甲基谷胱甘肽。 的km GSNO的γ-GT为28微摩尔。 存在下 污染过渡金属离子的γ-GT加速了释放 GSNO中的一氧化氮，因为CG-SNO更容易转化为 金属离子依赖的分解比GSNO。 然而，在存在 过渡金属离子螯合剂二亚乙基三胺五乙酸 在酸性条件下，GSNO和CG-SNO均不分解产生一氧化氮。 S-甲基谷胱甘肽和阿西维辛均不影响血管舒张功能。 在离体灌流的大鼠心脏中对GSNO的反应。 然而，老鼠 肾匀浆刺激GSNO的分解， acivicin-resistant机制 因此，γ-GT可能 参与肾脏中GSNO的分解，但不参与 心

S-Nitrosoglutathione (GSNO) has been used as a nitric oxide donor compound and has also been postulated to be involved in the transport of nitric oxide in vivo. In this study we have examined the possibility that GSNO is a substrate for gamma-glutamyl transpeptidase (gamma-GT), an enzyme that hydrolyses the gamma-glutamyl moiety of glutathione to give glutamate and cysteinylglycine. gamma-GT accelerated the decomposition of GSNO, forming S-nitrosocysteinylglycine (CG-SNO) by a mechanism inhibitable by the gamma-GT inhibitors acivicin and S-methylglutathione. The Km of gamma-GT for GSNO was found to be 28 micromole. In the presence of contaminating transition metal ions, gamma-GT accelerated the release of nitric oxide 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 nitric oxide. Neither S-methylglutathione nore 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 gamma-GT is involved in the decomposition of GSNO in the kidney but not in the heart.