A LECTIN FROM THE ASIAN HORSESHOE-CRAB TACHYPLEUS-TRIDENTATUS - PURIFICATION, SPECIFICITY AND INTERACTION WITH TUMOR-CELLS

A lectin from the haemolymph of the Asian horseshoe crab Tachypleus tr identatus was purified to homogeneity by affinity chromatography on Se pharose 4B-bound N-acetylneuraminic acid. The specificity of this lect in was studied by haemagglutination inhibition with sialic acid analog ues, N-acetylhexosamines and glycoproteins. For the interaction with t he agglutinin the N-acetyl group and the glyceryl side chain of N-acet ylneuraminic acid are important, while presence of an aglycon, special ly an a-glycosidically linked lactose increases affinity to the lectin . The strongest glycoprotein inhibitors were ovine as well as bovine s ubmaxillary mucin and Collocalia mucin, all being O-chain glycoprotein s but carrying completely different carbohydrate chains. The majority of N-chain proteins were inactive. As the lectin agglutinates human er ythrocytes, but not the murine lymphoma lines Eb and ESb or the human colon carcinoma HT 29, these cancer cells apparently lack the 'Tachypl eus tridentatus agglutinin-receptor' which is present on red cells and O-chain glycoproteins.