PURIFICATION AND CHARACTERIZATION OF 4 CA2-DEPENDENT LECTINS FROM THEMARINE INVERTEBRATE, CUCUMARIA-ECHINATA()

Four Ca2+-dependent, N-acetylgalactosamine/galactose-specific lectins were purified from the marine invertebrate, Cucumaria echinata (Holoth uroidea), by column chromatography on lactosyl-Sepharose 4B, Sephacryl S-200, and Q-Sepharose. The molecular masses of these lectins were es timated to be 27 kDa (CEL-I), 35 kDa (CEL-II), 45 kDa (CEL-III), and 6 8 kDa (CEL-IV) on SDS-PAGE under nonreducing conditions. Among these l ectins, CEL-I and CEL-IV strongly agglutinated rabbit and human erythr ocytes, and were found to recognize N-acetylgalactosamine and galactos e-containing carbohydrates from the results of a hemagglutination inhi bition assay. In contrast, CEL-II failed to agglutinate any erythrocyt es tested, although its carbohydrate-binding ability was confirmed by a carbohydrate-binding assay involving asialofetuin-horseradish peroxi dase. Interestingly, CEL-III caused hemolysis of rabbit and human eryt hrocytes, while it showed only hemagglutination of chicken and horse e rythrocytes at relatively high concentrations. The hemolytic activity of CEL-III was also dependent on the Ca2+-concentration, and inhibited by N-acetylgalactosamine and galactose-containing carbohydrates, sugg esting that the hemolysis was caused by Ca2+-dependent binding of CEL- III to specific carbohydrate chains on the erythrocyte surface and the following partial destruction of the membrane.