Pulse radiolysis studies of the reactions of nitrogen dioxide with the vitamin B12 complexes cob(II)alamin and nitrocobalamin.
Pulse radiolysis studies of the reactions of nitrogen dioxide with the vitamin B12 complexes cob(II)alamin and nitrocobalamin.
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二氧化氮与维生素 B12 复合物 cob(II)alamin 和硝基钴胺素反应的脉冲放射分解研究。
DOI：
10.1016/j.jinorgbio.2014.09.014
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发表时间：
2015
影响因子：
3.9
通讯作者：
Brasch,NicolaE
中科院分区：
文献类型：
--
作者：
Dassanayake,RohanS;Cabelli,DianeE;Brasch,NicolaE
虽然目前被认为是生物系统中重要的活性氮物种，可以改变蛋白质、DNA和脂质的结构，但对˙NO2的反应性，包括˙NO2与过渡金属配合物之间的反应的研究很少。我们报道了˙NO2与两种形式的维生素B12 - cob(II)alamin和nitrocobalamin反应的动力学研究。产物溶液的紫外-可见光谱和高效液相色谱分析表明，˙NO2可使cob（II）钴胺的金属中心氧化生成硝钴胺，其二级速率常数为（3.5±0.3）× 10⁸M⁻¹（pH 7.0和9.0，RT, I = 0.20 M）。该反应的化学计量比为1:1。当硝基钴胺暴露于2.0 mol当量˙NO2时，通过紫外可见光谱和高效液相色谱对产物溶液进行分析，未发现任何反应。
Although now recognized to be an important reactive nitrogen species in biological systems that modifies the structures of proteins, DNA and lipids, there few studies on the reactivity of ˙NO2, including the reactions between ˙NO2 and transition metal complexes. We report kinetic studies on the reaction of ˙NO2 with two forms of vitamin B12 – cob(II)alamin and nitrocobalamin. UV-vis spectroscopy and HPLC analysis of the product solution show that ˙NO2 cleanly oxidizes the metal center of cob(II)alamin to form nitrocobalamin, with a second-order rate constant of (3.5 ± 0.3) × 10⁸ M⁻¹ s ⁻¹ (pH 7.0 and 9.0, RT, I = 0.20 M). The stoichiometry of the reaction is 1:1. No reaction is detected by UV-vis spectroscopy and by HPLC analysis of the product solution when nitrocobalamin is exposed to up to 2.0 mol equiv.˙NO2.