Characterization of N<sup>α</sup>-Fmoc-protected dipeptide isomers by electrospray ionization tandem mass spectrometry (ESI-MS<sup>n</sup>): effect of protecting group on fragmentation of dipeptides
作者:M. Ramesh、B. Raju、R. Srinivas、V. V. Sureshbabu、T. M. Vishwanatha、H. P. Hemantha
DOI:10.1002/rcm.5076
日期:2011.7.30
and Y=CH(3)/H), have been characterized and differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-IT-MS(n)). In contrast to the behavior of reported unprotected dipeptide isomers which mainly produce y(1)(+) and/or a(1)(+) ions, the protonated Fmoc-Xxx-Gly-OY, Fmoc-Ala-Xxx-OY and Fmoc-Xxx-Ala-OY yield significant b(1)(+) ions. These ions are formed
Fmoc保护的二肽,Fmoc-Gly-Xxx-OY / Fmoc-Xxx-Gly-OY(Xxx = Ala,Val,Leu,Phe)和Fmoc-Ala-Xxx-OY / Fmoc-Xxx的一系列位置异构对-Ala-OY(Xxx = Leu,Phe)(Fmoc = [(9-芴基甲基)氧基]羰基和Y = CH(3)/ H)的特征在于,正离子和负离子电喷雾电离离子-阱串联质谱(ESI-IT-MS(n))。与主要产生y(1)(+)和/或a(1)(+)离子的未保护二肽异构体的行为相反,质子化的Fmoc-Xxx-Gly-OY,Fmoc-Ala-Xxx-OY和Fmoc-Xxx-Ala-OY产生明显的b(1)(+)离子。形成这些离子,大概具有稳定的质子化叠氮醌结构。但是,在N端带有Gly-的肽不会形成b(1)(+)离子。所有肽的[M + H](+)离子都会经历McLafferty型重排,然后损失CO(2)形成[M