PURIFICATION AND PRELIMINARY CHARACTERIZATION OF LECTINS FROM THREE COLOR STRAINS OF THE RED MARINE ALGA, KAPPAPHYCUS ALVAREZII (DOTY) DOTY EX SILVA

Abstract

The three lectins, named KAA-l, KAA-2 and KAA-3 after the specific name of alga, were isolated from each color strains of the red marine alga Kappaphycus alvarezii  by combination of gel filtration and ion exchange chromatography from the 80% cold ethanol precipitates. The highest yield of KAAs was 42.8 Ilg.g- 1 fresh tissue for the red strain, next was 31.8 μg.g^-l fresh tissue for the green strains, and the lowest was 30.2 μg.g^-l. fresh tissue for brown strains. The leetins had a molecular mass of 28000 ± 500 Da on SDS-PAGE in both non-reducing and reducing condition, respectively. Biochemical studies revealed that KAA-J and KAA-2 are monomeric proteins without a carbohydrate moiety, and had almost identical 20 N-tenninal amino acid sequence to each other, and only differed in the isoelectric point, indicating that they are isolectins to each other. The hemagglutination activities of KAAs were inhibited strongly by glycoproteins bearing high mannose type N-glycan as porcine thyroglobulin and yeast mannan so far as tested. The activities of KAAs were not affected by either the presence of EDT A or addition of divalent cations, was stable in a wide pH range from 3 to 10, and was not changed by incubation at 50°C for 30 min.