Activity and preliminary characterization of Branchiostoma lanceolatum agglutinin

The physical and chemical properties of a hemagglutinin from whole-body homogenates of the cephalochordate, Branchiostoma lanceolatum, are described. The hemagglutinin is proteinaceous since it is precipitated by trichloroacetic acid and ammonium sulphate, and all activity is lost at 60 degrees C or by treating with proteases. Carbohydrate moieties are probably also present since activity is lost after incubation with sodium metaperiodate. Activity is stable over pH 6-10. The agglutinin does not require Ca++ or Mg++, and a reduced titer after treatment with 2-mercaptoethanol and urea suggests the presence of both disulphide bonds and noncovalent linkages. Haemagglutination inhibition experiments with 17 saccharides and glycoproteins failed to show clear-cut carbohydrate specificity, with only mucin and fetuin having any inhibitory effect, so that the binding may be complex. Finally, cross-adsorption experiments suggest that only one lectin is present. The function of this lectin, especially in an immunobiological context, remains speculative.