电子捕获解离技术在生物质谱中的作用

ECD Technology in Biological Mass Spectrometry

电子捕获解离(ECD)是一种非各态历经的(non-ergodic)解离方式,可导致多肽中N—Cα键断裂,也能更优先断裂S—S键,在较高电子能量条件下还可以区分亮氨酸和异亮氨酸,并且在断裂过程中能完整保留蛋白质分子的修饰位点。因此,它与碰撞活化解离(CAD)等传统解离方式形成了较为理想的互补。ECD与CAD的联合使用可提供更广泛的多肽覆盖率序列信息,提高蛋白测序的效率与准确度。本文在介绍ECD基本原理、解离机理的基础上,简要地总结了ECD技术在生物质谱中的作用。

Electron capture dissociation （ECD） which is believed to be non-ergodic process is a new fragmentation technique used in Fourier transformation cyclotron resonance mass spectrometry and is complementary to conventional tandem mass spectrometry techniques. Its cleavage preferentially happens not only on N--Cα bond but also on disulfide bonds （S--S） in polypeptides, which are normally stable to vibrational excitation. The labile post-translational modifications and non-covalent bonds often remain intact after backbone bond dissociation. ECD provides more extensive sequence coverage in polypeptides, and at higher electron energies even isoleucine and leucine are distinguishable. The combination of CAD and ECD improves protein identification and enables high- throughput de novo sequencing of proteins. An overview of the principle and mechanism of ECD as well as its application in biological mass spectrometry is given.