Novel peptidylglycans with hemagglufinating activity-chemical structure and biological activity

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We found that eleven species of marine algae possessed novel hemagglutinins, which could not be extracted with phosphate buffered saline, unless the algae had been pretreated with Pronase. The novel hemagglutinins have been isolated from the Pronase-treated extracts of the red algae, Gelidium amansii and Carpopeltis flabellata, respectively. The 'Pronase treatment-dependent' hemagglutinins were commonly peptidylglycans with the apparent molecular weight of 8 x 10^5, respectively. As to glycan moieties, the major monosaccharides were Gal and Xyl, and uronic acids, 3,6-anhydro-galactose and sulfate esters also detected as the constituents. The peptide moieties share similar amino acid composition rich in Ser, Gly and Glx, suggesting that Xyl-Ser linkages in their molecules, respectively.The 'Pronase treatment-dependent' hemagglutinins markedly agglutinated sheep erythrocytes, especially trypsin- or Pronase treated ones, and also showed mitogenic activity for splenic lymphocytes of mice. They were stable at a high temperature and in a wide range of pH with rather increase at a low pH. The activity was weakly inhibited by asialofetuin and NaCl,but not by other sugar compounds tested. The activity was not affected by periodic acid oxidation or under the dissociation state with 4M guanidine-HCl as well as digestion with enzymes such as protease, glycosidases and sulfatase, which suggest that they have chemical structures resistant to chemical or enzymatic attacks examined.