Catfish (Clarias batrachus) serum lectin recognizes polyvalent Tn [alpha-D-GalpNAc1-Ser/Thr], Talpha [beta-D-Galp-(1-->3)-alpha-D-GalpNAc1-Ser/Thr], and II [beta-D-Galp(1-->4)-beta-D-GlcpNAc1-] mammalian glycotopes.
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 74.65kDa 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 (GalNAcalpha1-Ser/Thr) at the molecular level and was 3.5 times higher than GalNAc. CBL interacted strongly with polyvalent Tn and Talpha (Galbeta1,3GalNAcalpha1-) as well as multivalent-II (Galbeta1,4GlcNAcbeta1-) 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, Talpha and II>>>>monovalent Tn > or = Me-alphaGalNAc>monovalent Talpha> Me-betaGalNAc>Me-alphaGal>monovalent T>GalNAc>monovalent F>monovalent II>Me-betaGal>Gal.
Singha
Biswajit
B
Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
Adhya
Mausumi
M
Chatterjee
Bishnu P
BP
D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry* / Q000378:metabolism*; D002397:Catfishes / Q000097:blood; D006023:Glycoproteins / Q000378:metabolism; D006384:Hemagglutination; D006801:Humans; D037102:Lectins / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008322:Mammals; D008970:Molecular Weight; D011485:Protein Binding; D021241:Spectrometry, Mass, Electrospray Ionization; D013379:Substrate Specificity
D015295:Antigens, Tumor-Associated, Carbohydrate; D006023:Glycoproteins; D037102:Lectins; C040286:Tn antigen