Novel fragmentation pathway for CID of (b(n) - 1 + Cat)+ ions from model, metal cationized peptides.
We report a new fragmentation pathway for the CID of (b3 - 1 + Cat)+ product ions derived from the model peptide AXAG, where X = beta-alanine, gamma-aminobutyric acid, epsilon-amino-n-caproic acid, or 4-aminomethylbenzoic acid. By changing the amino acid to the C-terminal side of the amino acid X, and incorporating 15N and 13C labeled residues at the same position, we conclude that the dissociation pathway most likely leads to a metal cationized nitrile. With respect to the various amino acids at position X, the putative nitrile product becomes more prominent, relative to the conventional (a3 - 1 + Cat)+ species, in the order beta-alanine < gamma-aminobutyric acid < epsilon-aminocaproic acid < 4-aminomethylbenzoic acid. The pathway is not observed for peptides with alpha-amino acids at position X. The product ion is observed most prominently during the CID of Li+ and Na+ cationized peptides, only to a small extent for Ag+ cationized peptides, and not at all from protonated analogues.
Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
Travis J
TJ
Cooper
Erach R
ER
Talaty
Michael J
MJ
Van Stipdonk
D002412:Cations / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008094:Lithium; D008670:Metals / Q000737:chemistry*; D009570:Nitriles / Q000032:analysis / Q000737:chemistry; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D040901:Proteomics / Q000295:instrumentation / Q000379:methods*; D012964:Sodium
D002412:Cations; D008670:Metals; D009570:Nitriles; D010455:Peptides; D008094:Lithium; D012964:Sodium