Ethyl esterification is a technique for the chemical modification of sialylated glycans, leading to enhanced stability when performing matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS), as well as allowing the efficient detection of both sialylated and non-sialylated glycans in positive ion mode. In addition, the method shows specific reaction products for α2,3- and α2,6-linked sialic acids, leading to an MS distinguishable mass difference. Here, we describe the ethyl esterification protocol for 96 glycan samples, including enzymatic N-glycan release, the aforementioned ethyl esterification, glycan enrichment, MALDI target preparation, and the MS(/MS) measurement.
Keywords: Cotton; Ethyl esterification (EE); Hydrophilic interaction liquid chromatography (HILIC); Linkage-specific; Mass spectrometry (MS); Matrix-assisted laser desorption/ionization (MALDI); N-glycan release; Peptide-N-glycosidase F (PNGase F); Sepharose; Sialic acid (N-acetylneuraminic acid); Solid-phase extraction (SPE); Stabilization.