Neutral Loss Is a Very Common Occurrence in Phosphotyrosine-Containing Peptides Labeled with Isobaric Tags.

ABSTRACT: While developing a multiplexed phosphotyrosine peptide quantification assay, an unexpected observation was made: significant neutral loss from phosphotyrosine (pY) containing peptides. Using a 2000-member peptide library, we sought to systematically investigate this observation by comparing unlabeled peptides with the two highest-plex isobaric tags (iTRAQ8 and TMT10) across CID, HCD, and ETD fragmentation using high resolution high mass accuracy Orbitrap instrumentation. We found pY peptide neutral loss behavior was consistent with reduced proton mobility, and does not occur during ETD. The site of protonation at the peptide N-terminus changes from a primary to a tertiary amine as a result of TMT labeling which would increase the gas phase basicity and reduce proton mobility at this site.

SUBMITTER: Everley RA 

PROVIDER: S-EPMC5479408 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature