Characterisation of oligosaccharides from a glycoprotein variant of human serum albumin (albumin Casebrook) using high-performance anion-exchange chromatography and nuclear magnetic resonance spectroscopy.

The characterisation of oligosaccharides present on albumin Casebrook, a glycoprotein variant of human serum albumin, which contains an N-linked oligosaccharide at an attachment site formed by a point mutation of 494 Asp-->Asn, is described. The monosaccharide compositional analysis of purified glycopeptides suggested the presence of complex biantennary carbohydrate structures. The oligosaccharides which were released by N-glycosidase-F appeared to be a single molecular species according to their retention on high-performance anion-exchange chromatography. The structure of the oligosaccharide was suggested by sequential exoglycosidase digestions and confirmed by proton nuclear magnetic resonance spectroscopy. It was concluded that the oligosaccharides were essentially homogeneous and consisted of an alpha(2-6)-desialylated complex biantennary glycan.