Vanin A F, Malenkova I V, Serezhenkov V A
Institute of Chemical Physics, Russian Academy of Sciences, Moscow.
Nitric Oxide. 1997 Jun;1(3):191-203. doi: 10.1006/niox.1997.0122.
Formation of S-nitrosothiols was demonstrated in 1-50 mM aqueous solutions of cysteine or glutathione (cys-NO or GS-NO, respectively) upon contact of thiols with gaseous nitric oxide under a pressure of 50-600 mm Hg and anaerobic conditions. The yield of S-nitrosothiols was increased by mixing with NO plus air at a molar ratio [NO]/[O2 from air] of no less than 40. In this instance, the S-nitrosothiol formation was optimum at a NO pressure of 100-150 mm Hg. The addition of 0.25 mM o-phenanthroline, a selective Fe2+ chelator, to thiol solutions prior to the treatment with NO or NO + air completely blocked the formation of S-nitrosothiols. On the other hand, this process was potentiated by the addition of Fe2+ but not Cu2+ ions. These data indicated a crucial influence of Fe2+ on the process. The contact of o-phenanthroline with S-nitrosothiols synthesized by a routine method (treatment of thiol solutions with the NO + NO2 mixture at pH <1) did not induce their degradation at pH 3-10. Moreover, o-phenanthroline strikingly enhanced the cys-NO stability at neutral pH. Cysteine, glutathione, and desferal, a selective Fe3+ chelator, exerted a similar effect on cys-NO. The stabilizing effect of thiols on cys-NO was accompanied by the formation of dinitrosyl-iron complexes with thiol-containing ligands containing admixed (intrinsic) iron (1-2 microM). The addition of Fe2+ at a concentration higher than 10 microM abolished the stabilizing effect of thiols on cys-NO. Therefore iron can induce both degradation and synthesis of S-nitrosothiols. According to the proposed mechanisms such opposite effects of iron on S-nitrosothiols are determined by the ratio between S-nitrosothiols, thiols, iron, and NO in the reaction system.
在50 - 600 mmHg压力和厌氧条件下，使硫醇与气态一氧化氮接触后，在1 - 50 mM的半胱氨酸或谷胱甘肽水溶液（分别为cys - NO或GS - NO）中证实了S - 亚硝基硫醇的形成。通过以不低于40的摩尔比[NO]/[空气中的O₂]与NO加空气混合，可提高S - 亚硝基硫醇的产率。在这种情况下，在100 - 150 mmHg的NO压力下，S - 亚硝基硫醇的形成最为适宜。在用NO或NO + 空气处理之前，向硫醇溶液中加入0.25 mM邻菲罗啉（一种选择性Fe²⁺螯合剂），可完全阻断S - 亚硝基硫醇的形成。另一方面，加入Fe²⁺而非Cu²⁺离子可增强此过程。这些数据表明Fe²⁺对该过程有至关重要的影响。邻菲罗啉与通过常规方法合成的S - 亚硝基硫醇（在pH <1下用NO + NO₂混合物处理硫醇溶液）接触，在pH 3 - 10时不会诱导其降解。此外，邻菲罗啉在中性pH下显著增强了cys - NO的稳定性。半胱氨酸、谷胱甘肽和去铁胺（一种选择性Fe³⁺螯合剂）对cys - NO有类似作用。硫醇对cys - NO的稳定作用伴随着与含有混合（固有）铁（1 - 2 microM）的含硫醇配体形成二亚硝酰铁配合物。加入浓度高于10 microM的Fe²⁺会消除硫醇对cys - NO的稳定作用。因此，铁可诱导S - 亚硝基硫醇的降解和合成。根据所提出的机制，铁对S - 亚硝基硫醇的这种相反作用取决于反应体系中S - 亚硝基硫醇、硫醇、铁和NO之间的比例。
