Covalent modifications of hemoglobin by nitrite anion: formation kinetics and properties of nitrihemoglobin.
Covalent modifications of hemoglobin by nitrite anion: formation kinetics and properties of nitrihemoglobin.
复制标题
亚硝酸根阴离子对血红蛋白的共价修饰：硝基血红蛋白的形成动力学和特性。
DOI：
10.1021/tx100242w
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发表时间：
2010
影响因子：
4.1
通讯作者：
Peterson,Jim
中科院分区：
文献类型：
--
作者：
Otsuka,Mai;Marks,SarahA;Winnica,DanielE;Amoscato,AndrewA;Pearce,LindaL;Peterson,Jim
在弱酸性条件下，过量亚硝酸盐与人血红蛋白a0好氧反应制备绿色亚硝化血红蛋白（α2β2四聚体，NHb）。建立了与亚硝酸盐、氢离子和氧浓度有关的反应速率方程：−d[HbNO2]/dt= [k1+k2(Ka[HNO2])[O2]1/2][HbNO2]，其中k1=（2.4±0.9）× 10−4s−1,k2=（1±0.2）× 105M−5/2s−1，kais为亚硝酸盐的酸解离常数（4.5 × 10−4M）。此外，将NHb的化学性质与正常血红蛋白的化学性质进行比较（包括与外源配体的常见氧化态的加成产物，铁形式的碱性转变以及铁形式的氧结合特性），发现几乎无法区分。因此，在血红蛋白中每个大循环的外围用硝基取代单个乙烯基氢不会显著干扰血红素和血红素口袋之间的相互作用。由于非光化学反应化学必然最依赖于电子基态，因此血红蛋白a0和NHb之间明显可见的颜色差异必然主要与各自的电子激发态有关。考虑了NHb在体内形成的可能性及其可能的后果。
The green nitrihemoglobin (α2β2tetramer, NHb) was prepared by the aerobic reaction of excess nitrite with human hemoglobin A0under mildly acidic conditions. A rate equation was determined and found to depend on nitrite, hydrogen ion, and oxygen concentrations: −d[HbNO2]/dt= [k1+k2(Ka[HNO2])[O2]1/2][HbNO2], wherek1= (2.4 ± 0.9) × 10−4s−1,k2= (1 ± 0.2) × 105M−5/2s−1, andKais the acid dissociation constant for nitrous acid (4.5 × 10−4M). Also, the chemical properties of NHb are compared to those of the normal hemoglobin (including the addition products of common oxidation states with exogenous ligands, the alkaline transitions of the ferric forms, and the oxygen binding characteristics of the ferrous forms) and were found to be nearly indistinguishable. Therefore, the replacement of a single vinyl hydrogen with a nitro group on the periphery of each macrocycle in hemoglobin does not significantly perturb the interaction between the hemes and the heme pockets. Because nonphotochemical reaction chemistry must necessarily be most dependent on electronic ground states, it follows that the clearly visible difference in color between hemoglobin A0and NHb must be associated primarily with the respective electronic excited states. The possibility of NHb formation in vivo and its likely consequences are considered.