Abstract:
In some invertebrate marine animals, lectin or agglutinin possesses defense properties against other marine animals. We examined the lectins toward hemagglutinating activity of human and animal erythrocytes, sugar-binding specificities, and effect of heat and divalent cations requirement to elucidate the biochemical properties of the sponge lectins. The preliminary screening for the hemagglutinating activity in 48 marine sponges was carried out by extraction of the fresh sponges using 0.85% NaCl. It was found that the protein extracts from nine sponges’ species gave more high agglutinating activity against trypsin or papain- treated human erythrocytes more than normal erythrocytes. However, the protein extracts obtained from three species of sponges, i.e., Chondrilla australiensis, Hyrtios erecta, and Callyspongia (Euplacella) joubini, contained high activity of hemagglutinin specific to normal human A erythrocytes with titers approximately at 12,049, 1,965, and 1,932/mg protein, respectively.
Results of sugar-binding specificities assays performed with several carbohydrates and glycoproteins showed that the lectins from C. australiensis, H. erecta, and C. (Euplacella) joubini were specifically bound to glycoprotein, porcine stomach mucin, and fetuin more than mono- or oligosaccharide. The hemagglutinating activity of lectin derived from C. australiensis, and H. erecta was stabilized at 25-50๐C and of C. (Euplacella) joubini was stabilized at 25- 35๐C. The activity of lectin from H. erecta could be enhanced by magnesium ion.
