About the Lectin

The albumin gland of the edible snail Helix pomatia contains an anti-A blood group specific lectin which appears to be almost identical to the lectin isolated from Helix aspersa (HAA). Purified HPA is a glycoprotein with an interesting composition. The lectin is composed of 3 dimers. The identical subunits of each dimer are joined by a disulfide bond and the three dimers are held together by non-covalent forces 1 . Each subunit contains a single carbohydrate binding site. Carbohydrate inhibition studies indicate that the lectin reacts weakly with α-galactose, and that α-GalNAc is the best monosaccharide inhibitor. The lectin shows a strong preference for α- over β-linked structures and these results correspond well with the results obtained using purified HAA. The lectin shows a very low binding affinity for glucose, but it will bind well to a polyglucose gel matrix 2 . The same observation has been made for HAA. Neuraminidase treated T-lymphocytes of several species will bind the lectin while similarly treated B cells will not. Immobilized HPA has been used to preferentially isolate desialylated T lymphocytes from B lymphocytes by affinity chromatography 3 . The lectin has also been used in cell binding studies on several urinary bladder carcinoma cell lines and an osteogenic sarcoma cell line 4 . HPA reacts selectively with breast and colon cancer cell lines of high metastatic potential and is thus a good indicator of poor prognosis for these cancers, 5 but it is not selective for squamous cell carcinoma lines. 6 Although GlcNAc residues of hyaluronic acid bing the lectin, the selectivity lies in its GalNAc binding specificity. 7 HPA is also as effective as monoclonal antibodies for the detection and differentiation of herpes simplex virus types 1 and 2. 8

REFERENCES

  1. Hammarstrom, S., et al. (1972). Scand. J. Immunol.1 : 295-309.
  2. Ishiyama, I. and Uhlenbruck, G. (1971). Zeitschrift fur Naturforschung. 26b : 1198-1199.
  3. Sharon, N. (1983). Adv. Immunol. 34 : 213-298.
  4. Ishiyama, I. and Uhlenbruck, G. (1972). Comp. Biochem.Physiol. 42A : 269-276.
  5. Schumacher, U. (1997) Histochem. J. 29 : 677-684.
  6. Schumacher, D. U., et al. (1996) Eur. J. Surg. Oncol. 22 : 618-620.
  7. Schumacher, U., et al. (1996) Acta Histol. 98 : 435-440.
  8. Slifkin, M. and Cumbie, R. (1989) J. Clin. Microbiol. 27 : 1036-1039.

Product Characteristics
Buffer 0.01M Tris – 0.15M NaCl, pH 8.0.
Blood Group A1, A2.
Activity Less than 0.5 μg/ml will agglutinate A1 or A2 cells. Neuraminidase treated B and O cells react as strongly as type A cells.
Inhibitory Carbohydrate N-acetyl‑D‑galactosamine.
Molecular Weight Aggregate MW=79,000. Subunit MW=13,000.