Citrulline Effect Is a Characteristic Feature of Deiminated Peptides in Tandem Mass Spectrometry

Arnold Steckel, Gitta Schlosser

Research output: Contribution to journalArticle

1 Citation (Scopus)


Tandem mass spectrometry of peptides is of utmost importance in proteomics. Collision-induced dissociation usually generates y type fragment ion series from tryptic peptides, carrying information on their primary structure. Amino acid side chains or differences in their basicity could alter fragmentation processes considerably. The well-known proline effect is a cleavage preference at the N-terminus of proline residues in peptides, usually yielding a very abundant y ion while suppressing others. Previously, we reported a similar phenomenon occurring at the C-terminus of citrulline residues and coined the term Cit effect. To confirm the presence of Cit effect in large proteomic datasets, we analyzed 293 peptides containing Cit residues based on the human proteome database mining work of Lee et al. (2018). The occurrence of Cit effect was found to be 44%. Comparing bond scissions at the amide linkage between Cit-Zzz (citrulline followed by a specified residue) to Aaa1-Aaa2 (Aaa can be any residue except Cit), 5 Cit-Zzz cleavages were significantly (CL = 95.0%) more frequent in > 85% of the cases in terms of relative sequential base beak occurrence. We used Pro effect to compare with Cit effect and obtained very similar results. On the other hand, our study showed that Cit effect is slightly inferior in the overall incidence to Pro effect (50% vs. 33%, CL = 95%) among deiminated peptides when Pro residues were also present in the sequence. Our results suggest that Cit effect is a characteristic feature and a possible biasing factor of deiminated peptides which can confirm the position of citrullination sites. [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)1586-1591
Number of pages6
JournalJournal of the American Society for Mass Spectrometry
Issue number9
Publication statusPublished - Sep 16 2019


  • Citrullination
  • Citrulline effect
  • MS/MS
  • Post-translational modification
  • Proline effect

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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