2e51: Difference between revisions
No edit summary |
No edit summary |
||
| Line 4: | Line 4: | ||
==Overview== | ==Overview== | ||
Basic winged bean agglutinin binds A-blood group substance with higher | Basic winged bean agglutinin binds A-blood group substance with higher affinity and B-blood group substance with lesser affinity. It does not bind the O substance. The crystal structures of the lectin, complexed with A-reactive and B-reactive di and tri saccharides, have been determined. In addition, the complexes of the lectin with fucosylated A-trisaccharides and B-trisaccharides and with a variant of the A-trisaccharide have been modeled. These structures and models provide valuable insights into the structural basis of blood group specificities. All the four carbohydrate binding loops of the lectin contribute to the primary combining site while the loop of variable length contributes to the secondary binding site. In a significant advance to the current understanding, the interactions at the secondary binding site also contribute substantially, albeit in a subtle manner, to determine the blood group specificity. Compared with the interactions of the B-trisaccharide with the lectin, the third sugar residue of the A-reactive trisacharide forms an additional hydrogen bond with a lysine residue in the variable loop. In the former, the formation of such a hydrogen bond is prevented by a shift in the orientation of third sugar resulting from an internal hydrogen bond in it. The formation of this bond is also facilitated by an interaction dependent change in the rotamer conformation of the lysyl residue of the variable loop. Thus, the difference in the interactions at the secondary site is generated by coordinated movements in the ligand as well as the protein. A comparison of the crystal structure and the model of the complex involving the variant of the A-trisaccharide results in the delineation of the relative contributions of the interactions at the primary and the secondary sites in determining blood group specificity. | ||
==About this Structure== | ==About this Structure== | ||
| Line 10: | Line 10: | ||
==Reference== | ==Reference== | ||
Generation of blood group specificity: | Generation of blood group specificity: new insights from structural studies on the complexes of A- and B-reactive saccharides with basic winged bean agglutinin., Kulkarni KA, Katiyar S, Surolia A, Vijayan M, Suguna K, Proteins. 2007 Aug 15;68(3):762-9. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17510954 17510954] | ||
[[Category: Psophocarpus tetragonolobus]] | [[Category: Psophocarpus tetragonolobus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Katiyar, S.]] | [[Category: Katiyar, S.]] | ||
[[Category: Kulkarni, K | [[Category: Kulkarni, K A.]] | ||
[[Category: Suguna, K.]] | [[Category: Suguna, K.]] | ||
[[Category: Surolia, A.]] | [[Category: Surolia, A.]] | ||
| Line 24: | Line 24: | ||
[[Category: sugar binding protein]] | [[Category: sugar binding protein]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:06:03 2008'' | ||
Revision as of 18:06, 21 February 2008
|
Crystal structure of basic winged bean lectin in complex with A blood group disaccharide
OverviewOverview
Basic winged bean agglutinin binds A-blood group substance with higher affinity and B-blood group substance with lesser affinity. It does not bind the O substance. The crystal structures of the lectin, complexed with A-reactive and B-reactive di and tri saccharides, have been determined. In addition, the complexes of the lectin with fucosylated A-trisaccharides and B-trisaccharides and with a variant of the A-trisaccharide have been modeled. These structures and models provide valuable insights into the structural basis of blood group specificities. All the four carbohydrate binding loops of the lectin contribute to the primary combining site while the loop of variable length contributes to the secondary binding site. In a significant advance to the current understanding, the interactions at the secondary binding site also contribute substantially, albeit in a subtle manner, to determine the blood group specificity. Compared with the interactions of the B-trisaccharide with the lectin, the third sugar residue of the A-reactive trisacharide forms an additional hydrogen bond with a lysine residue in the variable loop. In the former, the formation of such a hydrogen bond is prevented by a shift in the orientation of third sugar resulting from an internal hydrogen bond in it. The formation of this bond is also facilitated by an interaction dependent change in the rotamer conformation of the lysyl residue of the variable loop. Thus, the difference in the interactions at the secondary site is generated by coordinated movements in the ligand as well as the protein. A comparison of the crystal structure and the model of the complex involving the variant of the A-trisaccharide results in the delineation of the relative contributions of the interactions at the primary and the secondary sites in determining blood group specificity.
About this StructureAbout this Structure
2E51 is a Single protein structure of sequence from Psophocarpus tetragonolobus with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Generation of blood group specificity: new insights from structural studies on the complexes of A- and B-reactive saccharides with basic winged bean agglutinin., Kulkarni KA, Katiyar S, Surolia A, Vijayan M, Suguna K, Proteins. 2007 Aug 15;68(3):762-9. PMID:17510954
Page seeded by OCA on Thu Feb 21 17:06:03 2008