Catfish (Clarias batrachus) serum lectin recognizes polyvalent Tn [alpha-D-GalpNAc1-Ser/Thr], T alpha[beta-D-Galp-(1 -> 3)-alpha-D-GalpNAc1-Ser/Thr], and II [beta-D-Galp(1 -> 4)-beta-D-GlcpNAc1-] mammalian glycotopes

摘要

A new calcium dependent GalNAc/Gal specific lectin was isolated from the serum of Indian catfish, Clarias batrachus and designated as C. batrachus lectin (CBL). It is a disulfide-linked homodecameric lectin of 74.65 kDa subunits and the oligomeric form is essential for its activity. Binding specificity of CBL was investigated by enzyme-linked lectin-sorbent assay using a series of simple sugars, polysaccharides, and glycoproteins. GalNAc was more potent inhibitor than Gal; and alpha glycosides of both were more inhibitory than their beta counterparts. CBL showed maximum affinity for human tumor-associated Tn-antigens (GalNAc alpha 1-Ser/Thr) at the molecular level and was 3.5 times higher than GalNAc. CBL interacted strongly with polyvalent Tn and T alpha (Gal beta 1,3GalNAc alpha 1-) as well as multivalent-II (Gal beta 1,4GlcNAc beta 1-) antigens containing glycoproteins and intensity of inhibition was 10(3)-10(5) times more than monovalent ones. The overall specificity of CBL lies in the order of polyvalent Tn, T alpha and II monovalent Tn >= Me-alpha Gal-NAc > monovalent T alpha > Me-beta GalNAc > Me-alpha Gal > monovalent T > GalNAc > monovalent F > monovalent II > Me-beta Gal > Gal. (C) 2008 Published by Elsevier Ltd.