MALDI mass spectrometry-based sequence analysis of arginine-containing glycopeptides: improved fragmentation of glycan and peptide chains by modifying arginine residue

Abstract

This paper describes an improved method for the sequence analysis of Arg-containing glycopeptide by MALDI mass spectrometry (MS). The method uses amino group derivatization (4-aza-6-(2,6-dimethyl-1-piperidinyl)-5-oxohexanoic acid N-succinimidyl ester) and removal (carboxypeptidase B) or modification (peptidylarginine deiminase 4) of the arginine residue of the peptide. The derivatization attaches a basic tertiary amine moiety onto the peptides, and the enzymatic treatment removes or modifies the arginine residue. Fragmentation of the resulting glycopeptide under low-energy collision-induced dissociation yielded a simplified ion series of both the glycan and the peptide that can facilitate their sequencing. The feasibility of the method was studied using α1 -acid glycoprotein-derived N-linked glycopeptides, and glycan and peptide in each glycopeptide were successfully sequenced by MALDI tandem MS (MS/MS).

Keywords: MALDI-QIT MS; arginine removal; citrullination; glycopeptide.