S-nitrosohemoglobin:: A mechanism for its formation in conjunction with nitrite reduction by deoxyhemoglobin
S-nitrosohemoglobin:: A mechanism for its formation in conjunction with nitrite reduction by deoxyhemoglobin
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DOI：
10.1016/j.niox.2006.01.012
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发表时间：
2006-08-01
影响因子：
3.9
通讯作者：
Rifkind, Joseph M.
中科院分区：
文献类型：
--
作者：
Nagababu, Enika;Ramasamy, Somasundaram;Rifkind, Joseph M.
红细胞中S-亚硝基血红蛋白（SNOHb）的形成一直是该领域研究人员的主要争论点。我们已经描绘了一个新的机制，形成SNOHb耦合到亚硝酸盐还原脱氧血红蛋白链在低氧压力。该机制的建立需要开发利用Cu（II）和抗坏血酸的化学发光测定法，以直接测量亚硝基硫醇，而不受亚硝酸盐或血红素-NO的任何干扰。还原中间体与电子离域之间的血红素铁和结合NO.从这个中间体形成SNOHb在无氧的可能机制包括电子离域中间体的扩展以包括β-93半胱氨酸残基的作用。这种扩展的离域支持与未结合的NO的直接反应，同时产生SNOHb和血红蛋白（II）NO，当NO与高铁血红蛋白反应。因此，体内红细胞中发现的SNOHb可以解释为源于氧气压力降低时发生的亚硝酸盐还原。爱思唯尔公司出版
The formation of S-nitrosohemoglobin (SNOHb) in red cells has been a major point of contention among researchers in this field. We have delineated a new mechanism for the formation of SNOHb coupled to nitrite reduction by deoxygenated hemoglobin chains at low oxygen pressures. The establishment of this mechanism required the development of a chemiluminescence assay utilizing Cu(II) and ascorbic acid to directly measure nitrosothiols without any interference from nitrite or heme-NO. The formation of SNOHb was shown to involve a dominant nitrite-reduction intermediate with electron delocalized between the heme iron and the bound NO. The possible mechanisms for the formation of SNOHb from this intermediate in the absence of oxygen are discussed including the role for an expansion of the electron delocalized intermediate to include the beta-93 cysteine residue. This extended delocalization was supported by a direct reaction with unbound NO, simultaneously producing SNOHb and Hb(II)NO, when NO reacts with metHb. The SNOHb found in red cells in vivo can, thus, be explained as originating from nitrite reduction that takes place at reduced oxygen pressures. Published by Elsevier Inc.