Isolation and characterization of a lectin from the hemolymph of the cephalopod Octopus vulgaris (Lam.) inhibited by alpha-D-lactose and N-acetyl-lactosamine.

The hemolymph of Octopus vulgaris is known to contain a lactose-specific agglutinin. This has been isolated by a two-step affinity-chromatographical procedure using, firstly immobilized asialofetuin followed by its binding to and elution from Con A-Sepharose. The lectin is a glycoprotein with a carbohydrate content of about 8%, and has a molecular weight (M.W.) of 260 kDa. Disulfide bridges connect subunits of molecular weights ranging between 30-32 kDa and of differing isoelectric points (pH 6.4, 6.6, 7.0, 7.3). Ca++-ions are required for ligand binding of the lectin; the pH-optimum for binding reactions is between pH 8.2-8.5 as determined by precipitation experiments with asialofetuin. Heating to 60-80 degrees C reduces agglutinating activity which is completely destroyed at 90 degrees C.