Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science

Collision-Induced Dissociations of Deprotonated Dipeptide Methyl Esters Containing Serine or Threonine

ST Steinborner, AM Bradford, RJ Waugh, JH Bowie, DL Vollmer and ML Gross

Australian Journal of Chemistry 47(10) 1851 - 1857
Published: 1994


The collision-induced mass spectra (MS/MS) of (M - H)- ions derived from dipeptide methyl esters containing serine or threonine lack the characteristic backbone cleavage of the underivatized peptides (which provide primary sequencing data). Instead, competitive fragmentation occurs through the ester and α-side chain functions. For example, Ser methyl esters lose both CH2O (from the side chain) and MeOH ( MeO comes from the methyl ester). Isomeric dipeptides may be differentiated by competitive fragmentations; for example [ Gly Ser( OMe )-H]- fragments first by loss of CH2O, while [Ser Gly ( OMe )-H]-, in contrast, shows initial elimination of MeOH. The structures of the product ions in these spectra have been probed by deuterium labelling and MS/MS/MS studies.

© CSIRO 1994

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