Perspectives in Biochemistry Solution Conformations of N-Linked Oligosaccharides+

A n integral feature of many cell surface and secreted pro-teins is the presence of one or more oligosaccharide units covalently linked to asparagine. Despite intensive investigation, the function of these oligosaccharides is in general unknown, although they have been implicated in a variety of biological systems. Of particular interest is their proposed role as rec-ognition signals in such processes as intracellular migration and secretion of glycoproteins (Sharon & Lis, 1982), biological activity of glycohormones (Calvo & Ryan, 1985), clearance of glycoproteins from circulation by hepatocytes (Morel1 et al., 1968; Prieels et al., 1978; Hudgin et al., 1974), and the metastasis of tumor cells (Dennis & Lafertg, 1985). As a first step toward an understanding of these and other postulated functions, attention has been focused upon oligosaccharide three-dimensional structure. High-resolution 'H NMR ' has been the primary tool for these investigations (Homans et al.