Tagging saccharides for signal enhancement in mass spectrometric analysis
Journal
Journal of Mass Spectrometry
Journal Volume
46
Journal Issue
3
Pages
247-255
Date Issued
2011
Author(s)
Liao, Sylvain Kuo-Shiang
Chen, Ying-Chu
Hung, Wei-Ting
Yu, Hui-Ming
Yang, Wen-Bin
Chen, Chung-Hsuan
Lee, Yuan Chuan
Abstract
AbstractMALDI?MS provides a rapid and sensitive analysis of large biomolecules such as proteins and nucleic acids. However, oligo? and polysaccharides are less sensitive in MS analysis partly due to their neutral and hydrophilic nature to cause low ionization efficiency. In this study, four types of oligosaccharides including aldoses, aminoaldoses, alduronic acids and �\?keto acids were modified by appropriate tags at the reducing termini to improve their ionization efficiency. Bradykinin (BK), a vasoactive nonapeptide (RPPGFSPFR), containing two arginine and two phenylalanine residues turned out to be an excellent MS signal enhancer for maltoheptaose, GlcNAc oligomers and oligogalacturonic acids. In the MALDI?TOF?MS analysis using 2,5?dihydroxybenzoic acid (2,5?DHB) as the matrix, the GalA4�VBK and GalA5�VBK conjugates prepared by reductive amination showed the detection limit at 0.1 fmol, i.e. ��800?fold enhancement over the unmodified pentagalacturonic acids. The remarkable MS enhancement was attributable to the synergistic effect of the basic arginine residues for high proton affinity and the hydrophobic property phenylalanine residues for facile ionization. A tetrapeptide GFGR(OMe) and an arginine linked phenylenediamine (H2N)2Ph?R(OMe) were thus designed to act as potent tags of oligosaccharides in MS analysis. Interestingly, concurrent condensation and lactonization of �\2,8?linked tetrasialic acid (SA4) was carried out with (H2N)2Ph?R(OMe) to obtain a quinoxalinone derivative, which showed > 200?fold enhancement over unmodified SA4 in the MALDI?TOF?MS analysis. Copyright ? 2011 John Wiley & Sons, Ltd.
SDGs
Type
journal article