Primary structure of a low-molecular-mass N-linked oligosaccharide from hemocyanin of Lymnaea stagnalis

3-O-methyl-d-mannose as a constituent of the xylose-containing core structure in an animal glycoprotein


Correspondence to J. F. G. Vliegenthart, Afdeling Bio-Organische Chemie, Rijksuniversiteit Utrecht, Transitorium III, Postbus 80.075, NL-3508 TB Utrecht, The Netherlands


Hemocyanin from the freshwater snail Lymnaea stagnalis is a high-molecular-mass copper-containing oxygen-transport protein, which occurs freely dissolved in the hemolymph. It is a glycoprotein contaning fucose, xylose, 3-O-methylmannose, 3-O-methylgalactose, mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine residues as sugar constituents. The N-glycosidic carbohydrate chains of this glycoprotein were released by hydrazinolysis of a pronase digest and subsequently fractionated as oligosaccharide-alditols on Bio-Gel P-4 followed by Lichrosorb-NH2. Investigation with 500-MHz 1H-NMR spectroscopy, in conjunction with sugar and methylation analysis revealed the lowest-molecular-mass glycan chain to have the structure: