Physical Chemistry Department and Institute of Electrochemistry, University of Alicante, 03690 San Vicente del Raspeig, Alicante, Spain.
Arch Biochem Biophys. 2013 Jan 1;529(1):26-33. doi: 10.1016/j.abb.2012.10.013. Epub 2012 Nov 27.
Nitration in proteins is a physiologically relevant process and the formation of 3-nitrotyrosine was first proposed as an in vivo marker of the production of reactive nitrogen species in oxidative stress. No studies have been published on structural changes associated with nitration of myoglobin. To address this deficiency the electrochemical nitration of equine skeletal muscle (Mb) at amino acid tyrosine 103 has been investigated for the evaluation and characterization of structural and thermal stability changes. Y103 in Mb is one of the most exposed tyrosine residues and it is also close to the heme group. Effects of Y103 nitration on the secondary and tertiary structure of Y103 have been studied by UV-Vis, circular dichroism, fluorescence and NMR spectroscopy and by electrochemical studies. At physiological pH, subtle changes were observed involving slight loosening of the tertiary structure and conformational exchange processes. Thermal stability of the nitrated protein was found to be reduced by 5 °C for the nitrated Mb compared with the native Mb at physiological pH. Altogether, NMR data indicates that nitrated Mb has a very similar tertiary structure to that of native Mb, although with a slightly open conformation.
蛋白质的硝化作用是一种生理相关的过程，3-硝基酪氨酸的形成最初被提议作为氧化应激中活性氮物种产生的体内标志物。目前还没有关于肌红蛋白硝化相关结构变化的研究。为了解决这一不足，已经研究了马骨骼肌肌红蛋白（Mb）在氨基酸酪氨酸 103 处的电化学硝化，以评估和表征结构和热稳定性变化。Mb 中的 Y103 是最暴露的酪氨酸残基之一，它也靠近血红素基团。通过紫外-可见光谱、圆二色性、荧光和 NMR 光谱以及电化学研究研究了 Y103 硝化对 Y103 二级和三级结构的影响。在生理 pH 值下，观察到涉及三级结构略微松动和构象交换过程的细微变化。与生理 pH 值下的天然 Mb 相比，硝化 Mb 的硝化蛋白的热稳定性发现降低了 5°C。总的来说，NMR 数据表明，硝化 Mb 的三级结构与天然 Mb 非常相似，尽管构象略微开放。
