title: Purification and properties of blood group A-active glycoprotein from oyster viscera.
abstract: A blood group A active substance was isolated from an acetone-dried powder of oyster viscera by extraction with 0.1 M NaCl after heating a homogenate with extraction medium, in boiling water. After the removal of the acidic fraction with cetylpyridinium chloride, the separated neutral fraction was digested successively with alpha-amylase and amyloglucosidase to remove glycogen. The blood group A-active portion was eluted from a Sepharose 4B column and purified by DEAE-Sephadex column chromatography. The purified active substance was homogeneous by polyacrylamide gel electrophoresis, and its molecular weight was estimated as 100 000 by sedimentation equilibrium. The sugar content of the purified active substance, expressed in percentage of dry weight, was galactosamine, 16.6; galactose, 12.5; fucose, 9.9; glucosamine, 4.6; and glucose, 3.3. Sialic acid was not detected. Total amino acid content was 23.0% and the main constituents were threonine, proline and serine. The ORD spectrum indicated that the hexosamines were N-acetylated. Absence of glycolipid was confirmed by the analysis of fatty acid and sphingosine base. This active substance had a strong blood group A activity (0.04 mug/ml) but neither B nor H activity; it interacted with lima bean lectin but not with concanavalin A.
mesh_terms: D000017:ABO Blood-Group System; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002942:Circular Dichroism; D004064:Digestive System / Q000032:analysis; D004912:Erythrocytes / Q000276:immunology; D006023:Glycoproteins / Q000276:immunology / Q000302:isolation & purification; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D008970:Molecular Weight; D009905:Optical Rotatory Dispersion; D010125:Ostreidae / Q000032:analysis*
chemical_list: D000017:ABO Blood-Group System; D000596:Amino Acids; D006023:Glycoproteins