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 .

REFERENCES

  1. Etzler, M. E. and Kabat, E. A. (1970). Biochemistry. 9 : 869-877.
  2. Borrebaeck, C. and Etzler, M. E. (1980). FEBS. Lett. 117 : 237 240.
  3. Etzler, M. E. (1973). Meth. Enzymol. 28 : 340-344.
  4. Etzler, M. E. (1994) Glycoconj. J. 11 : 395-399
  5. Etzler, M. E. (1994) Biochemistry 33: 9778-9783.
  6. Chao, Q. M., et al. (1994) Arch. Biochem. Biophys. 313 : 346-350.
  7. Imberty, A., et al. (1994) Glycoconj. J. 11 : 400-413.
  8. Gegg, C. V., et al. (1992) Biochemistry 31 : 6938-6942.
  9. Jacobs, L. R. and Huber, P. W. (1985). J. Clin. Invest. 75 : 112-118.
  10. Muramatsu, T., et al. (1980). Biochem. Biophys. Res.Comm. 96 :1547-1553.
  11. Watanabe, M., et al. (1981). J. Histochem. Cytochem. 29 : 779- 790.
  12. Farr, A. G., et al. (1998) J. Immunol. 140 : 1014-1021.
  13. Kasper, M., et al. (1994) Acta Histochem 96 : 63-73.

Product Characteristics
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.