About the Lectin
Daffodil bulbs contain high concentrations of a mannose specific lectin. The purified lectin does not react with human erythrocytes, but it does agglutinate untreated and trypsin treated rabbit erythrocytes 1 . Unlike the common mannose specific lectins (Con A, LcH, PSA, and VFA), NPA is not inhibited by glucose. NPA and a similar lectin from amaryllis bulbs(HHA) bind internal mannose residues as well as terminal mannosyl groups 2 . Several other lectins have been isolated in recent years which also exhibit specificity for mannose, and which do not react with glucose. These include the snowdrop, Galanthus nivalis 3 , the orchid twayblade, Listera ovata 4 , and the spring and summer snowflake, Leucojum vernum and L. aestivum1. NPA, snowdrop, and the two snowflake lectins all have similar molecular properties. Most have been cloned and sequenced, and have proved to be encoded by multigene families which show extensive homologies. 5 Antisera raised against either NPA or GNA will react with all four of these lectins. Although the four lectins appear homogeneous by SDS-PAGE, ion-exchange chromatography shows that they are all composed of several isolectins, each with the same molecular weight and carbohydrate specificity as the affinity purified lectin. These lectins differ in their reactivity with glycoproteins. Thyroglobulin is a better inhibitor of GNA than of NPA. NPA and L. aestivum are similar in reactivity, while GNA and L. vernum exhibit similar reactivities with glycoproteins. NPA is superior to GNA for isolation of human α-2 macroglobulin, but both lectins bind an unidentified protein that copurifies with α2 macroglobulin on affinity matrices 6 . NPA has been used alone or in conjunction with GNA in an ELISA assay for the HIV envelope glycoprotein gp120 7 , and to assess changes in human trophoblast glycolipids after ultrasound treatment 8 .
- Van Damme, E. J. M., et al. (1988) Physiologia Plantarum. 73 : 52- 57.
- Kaku, H., et al. (1990) Arch. Biochem. Biophys. 279 : 298-304.
- Van Damme, E. J. M., et al. (1987) FEBS Let. 215 : 140-144.
- Van Damme, E. J. M., et al. (1987) Plant Physiol. 85 : 566-569.
- Van Damme, E.J.M., et al. (1992) Physiologia Plantarum 86 : 245-252.
- Van Leuven, F., et al. (1993) Protein Sci. 2 : 255-263.
- Weiler, B.E., et al. (1991) J. Virol. Methods 32 : 287-301.
- Heffer-Lave, M., et al. (1995) Ultrasound Med. Biol. 21 : 579-584.
|Buffer||0.05M Tris – 0.1M NaCl, pH 8.0.|
|Blood Group||Non-reactive with human erythrocytes. NPA will agglutinate both normal and trypsin treated rabbit erythrocytes.|
|Molecular Weight||Aggregate MW=25,000 by gel filtration, 33,000 by ultracentrifugation. A single band of 12-13,000 Da by SDS-PAGE.|
|Caution||The purified, lyophiized lectin is only slightly soluble in water.|