Structural Characterization of the Carbohydrate Moieties of Glycoproteins by High-Resolution 1H-NMR

The biochemical/biomedical research community, the pharmaceutical industry, and, indeed, molecular biologists generally are faced with the increasing need for characterization of carbohydrate structures of recombinant glycoproteins and natural analogs. Cultured mammalian cells (such as Chinese hamster ovary [CHO] cells) are used to produce glycoproteins for therapeutic and diagnostic use because of their ability to perform glycosylation. The presence of oligosaccharide moieties is often compulsory to define several biological activities of glycoproteins, including clearance rate, immunogenicity, and specific biological activity. Since a number of factors that influence glycosylation still elude our control (such as culture environment and age of the cells), the same gene expressed in the same type of cell may not always yield a product with exactly the same glycosylation pattern, presenting drug batch quality-control problems for the pharmaceutical industry. Nuclear magnetic resonance (NMR) spectroscopy provides a powerful nondestructive means to characterize glycoprotein carbohydrates structurally and is an indispensable part of the current methodology of glycosylation site mapping.