Top-down analysis of highly post-translationally modified peptides by Fourier transform ion cyclotron resonance mass spectrometry

Andres Guerrero, Larry Lerno, Daniela Barile, Carlito B Lebrilla

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Bovine κ-caseinoglycomacropeptide (GMP) is a highly modified peptide from κ-casein produced during the cheese making process. The chemical nature of GMP makes analysis by traditional proteomic approaches difficult, as the peptide bears a strong net negative charge and a variety of post-translational modifications. In this work, we describe the use of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) for the top-down analysis of GMP. The method allows the simultaneous detection of different GMP forms that result from the combination of amino acid genetic variations and post-translational modifications, specifically phosphorylation and O-glycosylation. The different GMP forms were identified by high resolution mass spectrometry in both negative and positive mode and confirmation was achieved by tandem MS. The results showed the predominance of two genetic variants of GMP that occur as either mono- or bi-phosphorylated species. Additionally, these four forms can be modified with up to two O-glycans generally sialylated. The results demonstrate the presence of glycosylated, bi-phosphorylated forms of GMP never described before. [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)453-459
Number of pages7
JournalJournal of the American Society for Mass Spectrometry
Volume26
Issue number3
DOIs
StatePublished - 2015

Keywords

  • Caseinoglycomacropeptide
  • Fourier transform ion cyclotron resonance mass spectrometry
  • O-linked glycosylation
  • Phosphorylation
  • Top-down

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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