Arnelle D R, Stamler J S
Duke University Medical Center, Department of Respiratory Medicine, Durham, North Carolina 27710, USA.
Arch Biochem Biophys. 1995 Apr 20;318(2):279-85. doi: 10.1006/abbi.1995.1231.
The biological effects of S-nitrosothiols have been attributed to homolytic cleavage of the S-N bond with release of nitric oxide (NO.). Rates of NO. release from several S-nitrosothiols were determined by monitoring the oxidation of oxymyoglobin to metmyoglobin at pH 7.4; half-lives for oxymyoglobin oxidation ranged from seconds to hours. Transnitrosation reactions between S-nitrosothiols and thiol-containing amino acids, peptides, and proteins, which indicate the ability of nitrosothiols to act as nitrosyl (NO+) donors, occurred more rapidly than spontaneous NO. release. Decomposition of S-nitrosodithiols were examined as models for the reaction of nitrogen oxides with vicinal thiols on proteins. Rapid disulfide formation was accompanied by formation of hydroxylamine and nitrous oxide, indicative of nitroxyl (NO-) release. Taken together, these model studies demonstrate the ability of S-nitrosothiols to act as NO+, NO., and NO- donors under physiological conditions. Transnitrosation and acceleration of disulfide formation suggest mechanisms of regulation of protein function through the intermediacy of nitrosothiols, and support the notion that biological activities of S-nitrosothiols may be associated with heterolytic as well as homolytic mechanisms of decomposition.
S-亚硝基硫醇的生物学效应归因于S-N键的均裂并释放一氧化氮（NO·）。通过监测在pH 7.4条件下氧合肌红蛋白氧化为高铁肌红蛋白来测定几种S-亚硝基硫醇释放NO·的速率；氧合肌红蛋白氧化的半衰期从几秒到几小时不等。S-亚硝基硫醇与含硫醇的氨基酸、肽和蛋白质之间的转亚硝基化反应表明亚硝基硫醇作为亚硝酰基（NO+）供体的能力，其发生速度比自发释放NO·更快。研究了S-亚硝基二硫醇的分解，以此作为氮氧化物与蛋白质上的邻位硫醇反应的模型。快速形成二硫键的同时伴随着羟胺和一氧化二氮的形成，这表明释放了硝酰基（NO-）。综合来看，这些模型研究证明了S-亚硝基硫醇在生理条件下作为NO+、NO·和NO-供体的能力。转亚硝基化和二硫键形成的加速表明通过亚硝基硫醇介导调节蛋白质功能的机制，并支持S-亚硝基硫醇的生物学活性可能与异裂以及均裂分解机制相关的观点。
