Abstract

Human erythrocyte hemoglobin (Hb) has two reactive cysteines located on the surface of β-subunits. These cysteines play an important role in the adjustment of Hb functions. It is known that they are involved in the transport of intracellular nitric oxide (NO), redox signaling, and the regulation of dimeric-tetrameric Hb equilibrium. It is shown in this work that the incorporation of Cys-93β as ligands in iron-NO complexes is another way to regulate of SH group reactivity. Such complexes stabilize the SH group as a thiolate anion (R–S–), the reactivity of which is significantly higher than that of the protonated form of thiol (Cys-SH). This is why the thiols included in the complexes show increased activity in relation to electrophilic agents, such as ThioGlo1. Conversely, as part of the complexes, thiols are protected from oxidation by tert-butyl hydroperoxide. The incorporation of SH groups into complexes of iron and NO can be considered a means of thiol protection from irreversible oxidation upon oxidative stress.

中文翻译：

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一氧化氮铁配合物对血红蛋白半胱氨酸反应性的影响

摘要

人红细胞血红蛋白（Hb）在β亚基表面有两个反应性半胱氨酸。这些半胱氨酸在Hb功能的调节中起重要作用。已知它们参与细胞内一氧化氮（NO）的运输，氧化还原信号传导以及二聚体-四聚体Hb平衡的调节。在这项工作中表明，将Cys-93β作为配体掺入铁-NO配合物中是调节SH基团反应性的另一种方法。这样的络合物使SH基团稳定为硫醇根阴离子（R–S–），其反应活性明显高于质子化形式的硫醇（Cys-SH）。这就是络合物中包含的硫醇相对于亲电子试剂（如ThioGlo1）显示出更高活性的原因。相反，作为配合物的一部分，巯基被保护免受氧化叔丁基氢过氧化物。将SH基团掺入铁和NO的络合物中可以认为是硫醇保护免受氧化应激时不可逆氧化的一种手段。