About the Lectin
The lectin isolated from seeds of Dolichos biflorus is blood group A specific and has a specificity for terminal non-reducing N-acetyl-α-galactosamine. The purified lectin is specific for type A erythrocytes, although it is 50 times more reactive with type A1 cells 1 . DBA will precipitate streptococcal group C polysaccharide and will bind to porcine stomach mucin. The lectin can be fractionated by affinity chromatography on immobilized Con A into two isolectins, termed A and B 2 . The purified lectin is a glycoprotein as well as a metalloprotein containing Ca ++ , Mg ++ , Mn ++ , Zn ++ , and Cu ++ . The lectin is stable in solution at 4°C when stored below 3 mg/ml. DBA tends to aggregate when stored at higher concentrations 3 . A lectin isolated from vegetative tissue of D. biflorus (DB58) has similar, but distinct structural and carbohydrate-binding properties 4,5 . The seed lectin has been cloned and expressed in E. coli 6 , and its structure complexed with GalNAc and Gal NAc-containing oligosaccharides for which it has high affinity, GalNAcα1-3GalNAcβ-OMe (Forssman disaccharide) and GalNAcα1-3[Fucα1-2]Galβ-OMe (blood group A trisaccharide), has been modeled based on related legume lectin structure determined by X-ray crystallography 7 . Both lectins also have distinct binding sites for adenine derivatives, especially cytokinins such as 6-(benzylamino)purine 8 . The purified lectin has been used to study the changes in DBA receptors in colorectal mucin found in patients with inflammatory bowel disease 9 , in the study of receptors which can be used as a cell surface marker of a spontaneous leukemia 10 , in studying the distribution of lectin binding sites in mouse organ tissue 11 , and populations of mouse thymocytes 12 , and in characterizing types of aveolar cells 13 .
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|Buffer||0.01M Phosphate – 0.15M NaCl, pH 7.2-7.4|
|Blood Group||A1 >> A2|
|Activity||4 μg/ml will agglutinate human type A1 cells. As much as 200 μg/ml is needed to agglutinate type A2 cells.|
|Inhibitory Carbohydrate||Terminal α-N-acetyl‑D‑galactosamine.|
|Molecular Weight||Aggregate MW=110-120,000. A single band of MW=26-30,000 by SDS-PAGE.|