PURIFICATION AND CHARACTERIZATION OF 2 LECTINS FROM THE SEA-CUCUMBER STICHOPUS-JAPONICUS

Two Ca2+-dependent lectins were purified from the sea cucumber Stichop us japonicus by affinity chromatography on lactosyl-Sepharose 4B and i on-exchange chromatography on Q-Sepharose. Their molecular masses were estimated to be 13 kDa (SJL-I) and 15 kDa (SJL-II) on SDS-PAGE. SJL-I agglutinated rabbit erythrocytes as well as human A, B, and O-type er ythrocytes, but SJL-II agglutinated only rabbit erythrocytes. Hemagglu tination by SJL-I was competitively inhibited by N-acetyl-D-galactosam ine and galactose-containing carbohydrates. On the other hand, only la ctose, melibiose, and raffinose gave weak inhibition of hemagglutinati on by SJL-II, suggesting that SJL-II may have high specificity for par ticular complex carbohydrate(s) on the surface of rabbit erythrocytes. SJL-II was activated at ten times lower Ca2+ concentration than SJL-I . Both lectins lost activity in acidic pH, while SJL-I appeared more s table down to pH 4.5.