[Structure of the polysaccharide component of the bioglycan from the sea scallop Patinopecten uessoensis].

A bioglycan, [alpha]20D + 144 degrees (c 0.7, water), was isolated from the mantle of the scallop Patinopecten yessoensis, which is widespread in the Sea of Japan. The bioglycan represents a complex of alpha-D-glucan (83%) and protein (13%) and was homogeneous as judged by gel-filtration and ultracentrifugation. By means of molecular-sieve chromatography on Sepharose CL-4B, its average molecular weight was estimated as 4 MDa. Methylation studies, periodate oxidation and amylolysis showed that the polysaccharide part of the bioglycan consisted of alpha-1,4-linked D-glucopyranose residues, with side chains attached to every fourth sugar unit of the backbone through alpha-1,6-linkages (some side chains seem to be 1,3-linked). The structure of the bioglycan was confirmed by NMR spectral data. Amino acid composition of the protein part of the bioglycan was elucidated. The scallop bioglycan is related to the known bioglycans-immunomodulators of marine invertebrates with regard to the structure and immunological behaviour.