About the Lectin

The seeds of Bauhinia purpurea contain a lectin that will agglutinate
human erythrocytes regardless of their ABO and MN blood group type.
Treatment of the erythrocytes with neuraminidase or trypsin will
increase the agglutination reaction, indicating that the receptor is
masked by terminal carbohydrates 1 . Makela’s group 2 sugars,
and particularly N-acetyl-D-galactosamine, are potent inhibitors of the
lectin. Crude extracts were originally described as anti-N specific, but
after dialysis these preparations lose their anti-N specificity. The
native protein appears to be stable in detergent solution, unlike most
other purified lectins. A high molecular weight band of approximately
200,000 Da will appear using SDS-PAGE if the sample is not incubated in
SDS for at least 2 hours prior to electrophoresis. Longer exposure of
the lectin to SDS will degrade the protein into its subunit structure.
BPA has been cloned and sequenced. Its subunit sequence of MW=29,000
contains 5 potential glycosylation sites, 3 of which appear to be
occupied. It is highly homologous with other legume lectins 2 .
A nonapeptide sequence with affinity for Gal/GalNAc identified and
expressed in a chimetric protein probably represents the carbohydrate
binding site 3 . Purified BPA conjugated to suitable markers has been shown to specifically react with breast carcinomas 4 , to distinguish papillary and follicular carcinomas from normal cells and follicular adenomas in thyroid glands 5 , and to serve as a specific marker for Reed-Sternberg cells in Hodgkin’s disease 6 . It is a useful marker for several other cell types as well 7-9 .
Purified BPA has been used for the separation of a lectin binding
B-cell enriched preparation from murine splenocytes, and for isolation
of a non-agglutinating T-cell subset that produces IL-2 10 .

REFERENCES

  1. Irimura, T. and Osawa, T. (1972). Arch. Biochem. Biophys. 151 : 475-482.
  2. Kusui, K., et al. (1991) J. Biochem. 109 : 899-903.
  3. Yamamoto, K., et al. (1992) J. Chromatog. 597 : 221-230.
  4. Sarker, A. B., et al. (1995) Ind. J. Pathol. Microbiol. 38 : 261-265.
  5. Sarker, A. B., et al. (1994) Pathol. Res. Prac. 190 : 1005-1011.
  6. Sarker, A. B., et al. (1992) Amer. J. Pathol. 141 : 19-23.
  7. Sarker, A. B., at al. (1994) Ind. J. Pathol. Microbiol. 37 : 21-8.
  8. Kasper, M., et al. (1994) Exp. Toxicol. Pathol. 46 : 361-367.
  9. Shue, G.L., et al. (1993) Scand. J. Gastroenter. 28 : 599-604.
  10. Imai, Y. and Osawa, T. (1983). Scand. J. Immunol. 18 : 217-224.

Product Characteristics
Buffer 0.01M Phosphate -0.15M NaCl, pH 7.2-7.4
Blood Group Non-specific. M+N > O > A,B.
Activity Less than 0.5μg/ml will agglutinate neuraminidase treated human
erythrocytes. Without prior enzyme, at least 25 μg/ml is required to
agglutinate red blood cells.
Inhibitory Carbohydrate N-acetyl‑D‑galactosamine.
Molecular Weight BPA is a tetramer of MW = 195,000. Two strongly staining bands of 32,000 Da and 34,000 Da appear on SDS-PAGE.