Carbohydrate-Binding Activities of Agglutinins in Bivalves from the Sea of Japan

The hemolymph of bivalve mollusks is rich in a large variety of lectins and other carbohydrate-binding proteins that function as agglutinins and provide effective protection against pathogens abundant in the aquatic environment. Screening of the agglutinating activity of hemolymph plasma was carried out for 19 bivalves species from eight orders (Adapedonta, Myida, Cardiida, Venerida, Arcida, Mytilida, Pectinida, and Ostreida) of two infraclasses (Heteroconchia and Pteriomorphia). Twelve types of erythrocytes, including six from marine mammals, were used in the hemagglutination test, which has made it possible to identify the agglutinating activity in all samples and conduct a valid study of their carbohydrate specificity using the most suitable erythrocytes in a hemagglutination inhibition assay. The characteristic carbohydrate specificity of bivalves’ agglutinins to sialic and uronic acids, N-acetylated amines of glucose and galactose, mannan, and lactose has been shown. DL-Arabinose, D-xylose, D-glucurono-3,6-lactone, and α-methyl-D-glucopyranose have originally been found as specific molecular targets for proteins of some molluscan phylogenetic groups. These data foster isolation and identification of new carbohydrate-binding proteins capable of targeting specific glycosylation patterns valuable for biomedical and biotechnological applications.