碱性溶液中甲醇分子诱导的肌血球素构象变化

摘要

考察了不同pH值的碱性溶液中甲醇分子对诱导肌血球素构象变化的影响. 电喷雾电离质谱(ESI-MS)测量结果表明, 当pH分别为11.0, 11.4, 12.0时, 不同体积分数的甲醇(30%, 50%, 70%及90%)和水混合溶液将诱导肌血球素的构象变化. 当pH=11.0时, 肌血球素在溶液中均以hMb为主要形态存在(即血红素稳定存在于肌红蛋白中);当pH=11.4时, 30%甲醇中的肌血球素仍以hMb为主, 但升高甲醇比例会导致hMb上的辅基脱落生成aMb(蛋白质分子);当pH=12.0时, 溶液中的肌血球素均以aMb为主. 但当应用负离子质谱测量模式时, 检测出的肌血球素负离子均以aMb构象为主. 同时采用圆二色谱(CD)及紫外-可见(UV-Vis)光谱等研究发现, pH值和甲醇含量分别决定蛋白质分子的二级和三级结构的变化.%This paper reports the methanol-induced conformation change of myoglobin in basic solution. According to the results of mass spectrometry, we found that the conformation of myoglobin( Mb) changed in different volume fractions of methanol at pH =11.0, 11.4, 12.0. And both of the methanol concentration and pH value have some effect. Mb exists as hMb at pH =11.0, aMb at pH=12.0, aMb at pH=11.4 except in 30% volume fraction of methanol solution. Using negative ion mass spectrometry mode, Mb all show mainly as aMb. More information of Fe ion's coordination and electron spin state were found via CD spectrometry and UV-Vis Soret absorption.