Chemical Methods of Analysis of Glycoproteins

Abstract

The first analysis of glycoconjugates that often needs to be carried out is to see if they indeed contain sugar. For glycoproteins in gels or oligosaccharides in solution, this can be readily achieved by periodate oxidation at two concentrations, the first to detect sialic acids, and the second, any monosaccharide that has two free vicinal hydroxyl groups (1). Periodate cleaves between the hydroxyl groups to yield reactive aldehydes, which can be detected by reduction with NaB³H₄ or coupled to high sensitivity probes available in commercial kits, e.g., from Boeringher Mannheim (Mannheim, Germany) or Oxford Glycosystems (Abingdon, UK). In solution, a quick spot assay can be carried out for the presence of any monosaccharide or oligosaccharide having a C-2 hydroxyl group by visualization with charring by phenol/sulfuric acid reagent (2). These methods are relatively specific for mono/oligosaccharides (3).