Competitive formation of b(2) and c(2)-H2O ions from b(3) ions containing Asp residue during tandem mass spectrometry: the influence of neighboring Arg.
The fragmentation of b3 ions derived from protonated Arg-Xxx-Asp-Ala-Ala (Xxx = Ala, Asp, Glu, Cys) and Arg-Xxx-Glu-Ala-Ala was investigated by electrospray ionization tandem mass spectrometry (MS (n) ) with collision-induced dissociation. A particular ion, which is 1 Da less than b2 ion, is shown to be the c2-H2O ion. The mechanism for its formation involved the aspartic acid in the third position easily losing anhydride to form a c2 ion, which then lost water to form an eight-membered ring of azacyclooctane derivative under the participation of the guanidine of the N-terminal arginine. However, this phenomenon was not observed when the aspartic acid was replaced by glutamic acid. The Amber program was used to determine the conformation of the original c2 residue from the dynamic energy perspective, and then density functional theory-based calculations and changing N-terminal amino acid from arginine to phenylalanine supported this mechanism.
Department of Chemistry, Zhejiang University, Zheda road 38#, Hangzhou, 310027, China.
Mengzhe
M
Guo
Cheng
C
Guo
Yuanjiang
Y
Pan
D001120:Arginine / Q000737:chemistry*; D001224:Aspartic Acid / Q000737:chemistry*; D018698:Glutamic Acid / Q000737:chemistry; D019791:Guanidine / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D010649:Phenylalanine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014867:Water / Q000737:chemistry*
D007477:Ions; D014867:Water; D001224:Aspartic Acid; D018698:Glutamic Acid; D010649:Phenylalanine; D001120:Arginine; D019791:Guanidine