- 作者: Albert M. Wu
- 作者服務機構: Glyco-Immunochemistry Research Laboratory, Institute of Molecular and Cellular Biology, College of Medicine, Chang-Gung University, Kweishan, Taoyuan 333, Taiwan
- 中文摘要: --
- 英文摘要: The lectin extracted from the seeds of Salvia sclarea (SSL) recognizes the Tn antigen (GalNAcαl->Ser/Thr) expressed in certain human carcinomas. In previous studies, knowledge of the binding properties of SSL was restricted to GalNAcαl-> related oligosaccharides and glycopeptides. Thus, the requirements of functional groups in monosaccharide and high-density polyvalent carbohydrate structural units for SSL binding and an updated affinity profile were further evaluated by enzyme-linked lectinosorbent (ELLSA) and inhibition assays. Among the glycoproteins (gps) tested for interaction, a high density of exposed Tn-containing glycoproteins such as in the armadillo salivary Tn glycoprotein and asialo ovine salivary glycoprotein reacted best with SSL. When the gps were tested for inhibition of SSL binding, which was expressed as 50% nanogram inhibition, the high density polyvalent Tn present in macromolecules was the most potent inhibitor. Among the monosaccharide and carbohydrate structural units studied, which were expressed as nanomole inhibition, GalNAcαl->3GalNAcβl->3Galαl->4Galβl->4Glc (Fp), GalNAcαl ->3Galβ1->4Glc (AL), GalNAcαl->3GalNAcβl->Me (Fβ), GalNAcα 1->3GalNAcα 1->Me (Fα) and GalNAcαl-> Ser/Thr (Tn) were the most active ligands, being 2.5-5.0 x 103 and 1.25-2.5 times more active than Gal and GalNAc, respectively. From the results, it is suggested that the combining site of SSL is a shallow groove type, recognizing the monosaccharide of GalNAc as the major binding site or Tn up to the Forssman pentasaccharide (Fp). It can be concluded that the three critical factors for SSL binding are the -NH CH3CO at carbon-2 in Gal, the configuration of carbon-3 in GalNAc, and the polyvalent Tn (GalNAcα 1->Ser/Thr) present in macromolecules. These results should assist in understanding the glyco-rec-ognition factors involved in carbohydrate-lectin interactions in biological processes. The effect of the polyvalent Fα, Fβ and GalNAcβl->3Galαl-> (Pα) glycotopes on binding should be examined. However, this is hampered by the lack of availability of suitable reagents.
- 中文關鍵字: --
- 英文關鍵字: carbohydrate specificities, glycoprotein binding, lectins, multivalent effect, recognition factors, Salvia sclarea