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2-Phenyl-3-(p-aminophenyl) Acrylonitrile: A Reactive Matrix for Sensitive and Selective Analysis of Glycans by MALDI-MS

Ling, Ling, Xiao, Chunsheng, Ma, Yao, Jiang, Liyan, Wang, Sheng, Guo, Liming, Jiang, Shimei, Guo, Xinhua
Analytical chemistry 2019 v.91 no.14 pp. 8801-8807
2,5-dihydroxybenzoic acid, aldehydes, analytical specificity, blood serum, desorption, detection limit, glycoproteins, humans, ionization, matrix-assisted laser desorption-ionization mass spectrometry, nitriles, peptides, polysaccharides, tandem mass spectrometry
Analysis of glycans by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is usually limited by the intrinsically low abundance and low ionization efficiency of glycans. Aiming to enhance the ionization efficiency of glycans and simplify the sample preparation procedure during MALDI-MS analysis, we reported herein a novel reactive matrix, 2-phenyl-3-(p-aminophenyl) acrylonitrile (PAPAN), for sensitive and selective detection of glycans. PAPAN is a derivative of α-cyanocinnamic acid, which possesses high ionization efficiency in MALDI-MS. The PAPAN can react with the terminal aldehyde of glycans and thereby enable the significant enhancement of ionization efficiency of glycans. As a result, using PAPAN as a reactive matrix, the detection sensitivity for glycans was improved 100-fold compared with that using 2,5-dihydroxybenzoic acid (DHB) as the matrix. Meanwhile, the ionization of peptides can be significantly suppressed using PAPAN as the matrix, which allowed the selective detection of N-glycans from a deglycosylated tryptic digest of glycoprotein without any prepurification. Moreover, the PAPAN matrix also endowed the analysis of glycans with enhanced fragmentation during MS/MS analysis, which could facilitate glycan structure interpretation. Finally, PAPAN was successfully used for the analysis of N-glycome in human serum. Thus, a simple, sensitive, and selective method for the analysis of glycans has been achieved by using a novel reactive matrix, PAPAN.