光谱法对照研究肌红蛋白及其突变体Mb(D60K)与H2O2的相互作用

摘要

To characterize the roles played by surface-charged residue Asp60 in the structure stability of myoglobin when it was replaced with Lys, the interaction of myoglobin[Mb(WT)] and its mutant[Mb(D60K)] with hydrogen peroxide (H2O2) were studied by the method of ultraviolet-visible (UV-Vis) absorption spectroscopy, fluorescence spectroscopy and stopped-flow fluorescence spectroscopy under simulative physiological conditions. There are remarkable differences between Mb(D60K) and Mb (WT) in the UV-Vis absorption spectroscopy and fluorescence spectroscopy of iron porphyrin during the process of interaction. Although we only altered one external amino acide, the data showed that the function and structure stability of Mb(D60K) was greatly changed. Furthermore, results from synchronous fluorescence spectroscopy and stopped-flow fluorescence spectroscopy all indicated that H2Q2 had less effect on the structure of Mb(D60K) while the structure of Mb(WT) was notably changed. From a comprehensive and comparative data analysis, the authors determined that the structure of Mb(D60K) was improved when it interacted with H2O2.%为了解肌红蛋白(Mb)表面60位天冬氨酸(Asp)突变为赖氨酸(Lys)后对蛋白结构稳定性的影响,本文通过紫外-可见吸收光谱、荧光光谱和停流荧光光谱对照研究了模拟生理条件下野生型肌红蛋白Mb(WT)及其突变体Mb(D60K)与过氧化氢(H2O2)的相互作用.结果表明:在Mb(D60K)与H2O2发生相互作用过程中,铁卟啉部位的紫外和荧光发射光谱数据与Mb(WT)相比,性质与功能均表现出显著差异.虽然只有一个氨基酸的改变,但其结构和性质发生明显变化,说明60位氨基酸在稳定蛋白结构中有重要的作用.同步荧光光谱和停流光谱的结果同样表明Mb(D60K)的结构与功能受H2O2的影响较小,Mb(WT)受H2O2影响明显.综合分析表明,Mb(D60K)在与H2O2相互作用过程中,蛋白结构稳定性提高.