Mass spectral study of hybrid peptides derived from (R)-aminoxy ester and beta-amino acids: The influence of aminoxy peptide bond (CO-NH-O) on peptide fragmentation under electrospray ionization conditions

作者：Ramesh V; Ramesh M; Srinivas R^*; Sharma G V M; Manohar V

来源：International Journal of Mass Spectrometry, 2009, 282(1-2): 64-69.

DOI：10.1016/j.ijms.2009.02.006

• Aminoxy peptide bond
• Electrospray ionization
• Tandem mass spectrometry
• Hybrid peptide

A new class of Boc-protected aminoxy hybrid peptides containing repeats of beta-hAla-(R)-Ama-, and beta-Caa-(R)-Ama- (beta-hAla = beta(3)-(S)-hAlanine, (R)-Ama = (R)-aminoxy ester. and beta-Caa = (R)-C-linked carbo-beta(3)-amino acid) have been studied by electrospray ionization (ESI) ion-trap and quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) of their protonated, cationized, and negative ions. MS(3) CID of protonated aminoxy peptides of beta-hAla-(R)-Ama- yield intense beta-amino acid characteristic retro-Mannich fragmentation. The b(n)( ) and [b(n)-methyl imine]( ) (n = 3, 5) ions formed by cleavage of aminoxy peptide bond (CO-NH-O) are more intense than b(n)( ) (n = 2,4) formed by that of peptide bond (CO-NH-C) cleavage. Another characteristic ion observed is due to loss of H(3)NO from y(n)( ) ions. The cationized (Li( ), and Na( )) peptides dissociate differently compared to protonated peptides. Intense cationized c(n) and z(n) ions are formed due to the cleavage of N-O bond. The deprotonated peptides also show abundant C(n)(-) and Z(n)(-) ions (n = 1, 3, 5) and do not form any Y(n)(-) ions. All these results clearly indicate the influence of aminoxy peptide bond on fragmentation of these hybrid peptides.

• 出版日期2009-4-15