Gordge M P, Addis P, Noronha-Dutra A A, Hothersall J S
Institute of Urology and Nephrology, University College London, UK.
Biochem Pharmacol. 1998 Mar 1;55(5):657-65. doi: 10.1016/s0006-2952(97)00498-x.
Spontaneous release of nitric oxide (NO) from S-nitrosothiols cannot explain their bioactivity, suggesting a role for cellular metabolism or receptors. Using immortalised cells and human platelets, we have identified a cell-mediated mechanism for the biotransformation of the physiological S-nitrosothiol compound S-nitrosoglutathione (GSNO) into nitrite. We suggest the name "GSNO lyase" for this activity. GSNO lyase activity varied between cell types, being highest in a fibroblast cell line and lowest in platelets. In NRK 49F fibroblasts, GSNO lyase mediated a saturable, GSNO concentration-dependent accumulation of nitrite in conditioned medium, which was inhibited both by transition metal chelators, and by subjecting cells to oxidative stress using a combination of the thiol oxidant diamide and Zn2+, a glutathione reductase inhibitor. Activity was resistant, however, to both acivicin, an inhibitor of gamma-glutamyl transpeptidase (EC 2.3.2.2), and to ethacrynic acid, an inhibitor of Pi class glutathione-S-transferases (EC 2.5.1.18), thus neither of these enzymes could account for NO release. Although GSNO lyase does not explain the platelet-selective pharmacological properties of GSNO, cellular biotransformation suggests therapeutic avenues for targeted delivery of NO to other tissues.
亚硝基硫醇中一氧化氮（NO）的自发释放无法解释其生物活性，这表明细胞代谢或受体发挥了作用。我们利用永生化细胞和人血小板，确定了一种细胞介导的机制，可将生理性亚硝基硫醇化合物亚硝基谷胱甘肽（GSNO）生物转化为亚硝酸盐。我们建议将此活性命名为“GSNO裂解酶”。GSNO裂解酶活性在不同细胞类型间存在差异，在成纤维细胞系中最高，在血小板中最低。在NRK 49F成纤维细胞中，GSNO裂解酶介导条件培养基中亚硝酸盐的饱和、GSNO浓度依赖性积累，过渡金属螯合剂以及使用硫醇氧化剂二酰胺和谷胱甘肽还原酶抑制剂Zn2+组合使细胞遭受氧化应激均能抑制这种积累。然而，该活性对γ-谷氨酰转肽酶（EC 2.3.2.2）抑制剂阿西维辛和Pi类谷胱甘肽-S-转移酶（EC 2.5.1.18）抑制剂依他尼酸均具有抗性，因此这两种酶均无法解释NO的释放。尽管GSNO裂解酶无法解释GSNO的血小板选择性药理特性，但细胞生物转化为将NO靶向递送至其他组织提供了治疗途径。
