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Updated: Aug 21, 2026

Simultaneous Affinity Enrichment of Two Post-Translational Modifications for Quantification and Site Localization
Published on: February 27, 2020
Locating and identifying posttranslational modifications by in-source decay during MALDI-TOF mass spectrometry
1Department of Biochemistry, University of Washington, Seattle 98195-7350, USA.
Abstract:
A technique is described for identifying and locating posttranslational modifications (PTMs) in peptides and proteins of known sequence by interpretation of c(n) ion signals generated by in-source decay during delayed ion extraction in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Sites of phosphorylation in seven synthetic peptides were determined, as was the location of both the heme group and N,N,N-trimethyllysine in yeast cytochrome c. A semi-automated data analysis process facilitates the identification of segments of the sequence on each side of the PTM, permitting its placement at the junction of the segments and definition of the added mass. A graphical display facilitates illustration of both the location and mass of the PTM.
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