- 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 agglutinin isolated from the seeds of Madura pomifera (MPA) recognizes a mucin-type disaccharide sequence, Galβ1->3Ga1NAc (T) on a human erythrocyte membrane. We have utilized the enzyme-linked lectinosorbent assay (ELLSA) and inhibition assay to more systematically analyze the carbohydrate specificity of MPA with glyco-recognition factors and mammalian Gal/GalNAc structural units in lectin-glycoform interactions. From the results, it is concluded that the high densities of polyvalent Gal-NAcαl->Ser/Thr (Tn) and Galβ1->3GalNAcαl->Ser/Thr (Tα) glycotopes in macromolecules are the most critical factors for MPA binding, being on a nanogram basis 2.0 x 105, 4.6 x 104 and 3.9 x 104 more active than monovalent Gal, monomeric T and Tn glycotope, respectively. Other carbohydrate structural units in mammalian glycoconjugates, such as human blood group Sd (a + ) related disaccharide (GalNAcβl->4Gal) and Pk/P1 active disaccharide (Galαl->4Gal) were inactive. These results demonstrate that the configurations of carbon-4 and carbon-2 are essential for MPA binding and establish the importance of affinity enhancement by high-density polyvalencies of Tn/T glycotopes in MPA-glycan interactions. The overall binding profile of MPA can be defined in decreasing order as: high density of polyvalent Tn/TK (M.W. > 4.0 x 10^4) >> Tn-containing glycopeptides (M.W. < 3.0 x 10^3) > monomeric T/Tn and P (GalNAcβ1->3Gal) > GalNAc > Gal >> Man, LAra, dFuc and Glc (inactive). Our findings should aid in the selection of this lectin for elucidating functions of carbohydrate chains in life processes and for applications in the biomedical sciences.
- 中文關鍵字: --
- 英文關鍵字: carbohydrate specificities, glycoprotein binding, lectins, Maclura pomifera, multivalent effect, polyvalency