Thionitroxides, RSNHO*: the structure of the SNO moiety in "S-Nitrosohemoglobin", a possible NO reservoir and transporter.
Thionitroxides, RSNHO*: the structure of the SNO moiety in "S-Nitrosohemoglobin", a possible NO reservoir and transporter.
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DOI：
10.1021/ja057097f
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发表时间：
2006-02
影响因子：
15
通讯作者：
Yi-Lei Zhao;K. Houk
中科院分区：
文献类型：
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作者：
Yi-Lei Zhao;K. Houk
一氧化氮（NO）在许多生物过程中起着重要作用。长期以来，S-亚硝基硫醇被认为在NO生物化学中具有重要作用。血红蛋白的修饰半胱氨酸残基先前被鉴定为扭曲的S-亚硝基硫醇（RSNO）或S-羟氨基自由基（RSN*OH）。在这里，我们表明，硫氮氧化物（RSNHO*，S-aminyloxyl自由基）可能是观察到的物种。计算研究表明，硫代氮氧化物是唯一的结构与电子密度在血红蛋白Cysbeta 93-SNO结构先前报道。虽然是亚稳态加合物，但在氢键环境中的硫代氮氧化物可以容易地形成并在暴露于水性环境时释放NO。硫代氮氧化物可能是S-亚硝基硫醇生物效应的原因，也可能是S-亚硝基硫醇在氧化条件下的前体。
Nitric oxide (NO) plays important roles in many biological processes. S-Nitrosothiols have long been believed to have significant roles in NO biochemistry. The modified cysteine residue of hemoglobin was previously identified as a distorted S-nitrosothiol (RSNO) or an S-hydroxyamino radical (RSN*OH). Here we show that a thionitroxide (RSNHO*, S-aminyloxyl radical) is likely the observed species. Computational studies show that the thionitroxide is the only structure consistent with the electron density in the hemoglobin Cysbeta93-SNO structure previously reported. Although a metastable adduct, the thionitroxide in a hydrogen-bonding environment can form readily and release NO upon exposure to an aqueous environment. The thionitroxides could be responsible for the biological effects attributed to S-nitrosothiols or could serve as precursors to S-nitrosothiols in oxidative conditions.