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
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|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.|
|Molecular Weight||Aggregate MW=79,000. Subunit MW=13,000.|