Can alpha- and beta-Alanine Containing Peptides Be Distinguished Based on the CID Spectra of Their Protonated Ions?
Adrian KY Lam, Sri H Ramarathinam, Anthony W Purcell, Richard AJ Ohair
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY | SPRINGER | Published : 2008
The fragmentation reactions of isomeric dipeptides containing alpha- and beta-alanine residues (alphaAla-alphaAla, alphaAla-betaAla, betaAla-alphaAla, and betaAla-betaAla) were studied using a combination of low-energy and energy resolved collision induced dissociation (CID). Each dipeptide gave a series of different fragment ions, allowing for differentiation. For example, peptides containing an N-terminal beta-Ala residue yield a diagnostic imine loss, while lactam ions at m/z 72 are unique to peptides containing beta-Ala residues. In addition, MS(3) experiments were performed. Structure-specific fragmentation reactions were observed for y(1) ions, which help identify the C-terminal residu..View full abstract