摘要
电喷雾电离(ESI)技术由于脱溶剂过程中产生的电解作用及溶剂蒸发作用,使得酸性溶液喷雾液滴中质子残留,pH值降低,导致蛋白质在液滴中的空间构象受到破坏,所得质谱图无法正确反映蛋白质在溶剂中的真实构象。本研究以两种经典蛋白质(细胞色素C和肌红蛋白)为实验样本,通过在ESI源和质谱仪进样端中间加入自行设计的空气放大器,产生高流速大流量气流,改善ESI脱溶剂过程。结果表明,电喷雾电离的初始液滴在高流速大流量气流引发的激烈碰撞中,被切割为粒径极小的喷雾液滴,同时液滴所带电荷被均分,从而使液滴pH值保持稳定,避免因ESI脱溶剂作用而破坏蛋白质的空间构象。基于高流速大流量气流在ESI脱溶剂过程的新机理,在使用商业化的ESI源时,着重于鞘气等脱溶剂辅助气体的使用和调节。通过增大鞘气的气流量保持蛋白质的生物构象。
ESI could destroy the protein solution-phase conformation due to the change in pH of the spray droplets during the desolvation process, especially protein in acidic solution, in which mass spectrum wouldn＇ t present the natural protein confirmation in solution. In this study, two classic proteins, cytochrome C, and myoglobin, have been deliberately chosen as the experimental samples to understand and modify ESI desolvation process by introducing a large flow of high velocity airflow between the ESI emitter and the inlet of the mass spectrometer generated by a home-made air amplifier. The experiment results prove that when applying the large flow of high velocity airflow, the initial droplets sprayed from ESI experience a large number of collisions, which can cause fast fission with charges redistributed and a much faster desolvation than during normal ESI. The protein ions are quickly desolvated in the absence of a large excess of protons in the droplets, which avoid the acid-reduced denaturalization. Based on the new understanding to the desolvation process, the utilization and appropriate adjustment of the assistant gas in a commercial ESI source were discussed in this article. The increasing of shealth gas is preferred to retain the protein confirmation in ESI droplets.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期267-272,共6页
Chinese Journal of Analytical Chemistry
关键词
电喷雾电离
脱溶剂作用
蛋白质空间构象
喷雾液滴
Electrospray ionization
Desolvation
Protein conformation
pH of spray droplet
