This paper presents new results that confirm our previous inference that the binuclear form of biologically active dinitrosyl iron complexes (B-DNICs) with thiol-containing ligands (glutathione or N-acetyl-L-cysteine) may act as a donor of nitrosonium cations, which are responsible for S-nitrosothiol formation during B-DNIC decomposition in acid solutions under both aerobic and anaerobic conditions. The presence of nitrosonium cations within B-DNICs is determined by the dispropoportionation reaction of free-radical nitric oxide (NO) molecules while binding to Fe2+ cations (two molecules per one ion) during B-DNIC synthesis. When thiolic ligands are oxidized in DNICs or inactivated by thiol-specific reagents, the nitrosonium cations released during decomposition of these DNICs at neutral pH values are hydrolyzed and transformed to nitrite anions. A similar transformation occurs when mononuclear DNICs (M-DNICs) with nonthiolic ligands are decomposed at neutral pH values. It has been found that S-nitrosothiol formation in the decomposition of B-DNICs with thiolic ligands at acidic pH values can be inhibited by the presence of a two to threefold excess of free thiol molecules (outside the B-DNIC) with regard to the B-DNIC level. This inhibition is due to the reduction of nitrosonium cations induced by free thiol molecules and catalyzed by iron ions. The NO molecules that result from the reduction are released from the DNICs. Thus, both forms of DNICs, M and B, that form in living systems can act not only as donors of NO, which is now recognized as one of the universal regulators of metabolic processes, but also as donors of nitrosonium cations, which initiate S-nitrosation of low- and high-molecular-weight (protein-bound) thiols.

中文翻译：

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一氧化氮分子的自由基性质是它们在生命系统中转化为亚硝基阳离子的决定因素

本文提出的新结果证实了我们之前的推论，即具有含硫醇配体（谷胱甘肽或 N-乙酰-L-半胱氨酸）的生物活性二亚硝基铁配合物（B-DNICs）的双核形式可以作为亚硝基阳离子的供体，在有氧和无氧条件下，在酸性溶液中 B-DNIC 分解过程中，它们负责形成 S-亚硝基硫醇。B-DNIC 中亚硝基阳离子的存在是由自由基一氧化氮 (NO) 分子在 B-DNIC 合成过程中与 Fe2+ 阳离子（每个离子两个分子）结合时的歧化反应决定的。当硫醇配体在 DNIC 中被氧化或被硫醇特异性试剂失活时，这些 DNIC 在中性 pH 值下分解过程中释放的亚硝基阳离子被水解并转化为亚硝酸根阴离子。当具有非硫醇配体的单核 DNIC (M-DNIC) 在中性 pH 值下分解时，会发生类似的转变。已经发现，在酸性 pH 值下，具有硫醇配体的 B-DNIC 分解中 S-亚硝基硫醇的形成可以通过存在 2 到 3 倍过量的游离硫醇分子（在 B-DNIC 之外）来抑制。 B-DNIC 级别。这种抑制是由于游离硫醇分子诱导和铁离子催化的亚硝基阳离子的还原。还原产生的 NO 分子从 DNIC 中释放出来。因此，生命系统中的两种形式的 DNIC，M 和 B，不仅可以作为 NO 的供体（现在被认为是代谢过程的通用调节剂之一），而且还可以作为亚硝基阳离子的供体，