Purification and characterization of a lectin from the starfish Asterias amurensis

In this study, we describe a novel lectin (designated AMUL) from the Northern Pacific starfish Asterias amurensis. AMUL was purified from the coelomic fluid by affinity chromatography followed by size-exclusion chromatography. The native molecular mass of the lectin was found to be approximately 270 kDa by size-exclusion chromatography using a Superdex 200 column. AMUL showed distinct bands at approximately 14 or 18 kDa on SDS-PAGE under nonreducing or reducing conditions, respectively. The hemagglutination activity of AMUL against rabbit erythrocytes was strongly inhibited by the two sialic acids N-acetylneuraminic acid and N-glycolylneuraminic acid. The glycoproteins tested showed no inhibition of hemagglutination. The first 28 amino acid residues of AMUL were determined by automated Edman degradation, showing that AMUL has considerable sequence homology with C-type lectins from other echinoderms. These results show that AMUL is a novel echinoderm-derived sialic-acid-specific lectin that belongs to the C-type lectin superfamily.