Molecular recognition of sialyl Lewis(x) and related saccharides by two lectins

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Title Molecular recognition of sialyl Lewis(x) and related saccharides by two lectins
Author Haselhorst, Thomas Erwin; Weimar, Thomas; Peters, Thomas
Journal Name Journal of The American Chemical Society
Year Published 2001
Place of publication Easton, Pa.
Publisher American Chemical Society
Abstract The interaction of sialyl Lewis(x), Lewis(x), and α-L-Fuc-(1→3)-β-D-GlcNAc with isolectin A from Lotus tetragonolobus (LTL-A), and with Aleuria aurantia agglutinin (AAA) was studied using NMR experiments and surface plasmon resonance. Both lectins are specific for fucose residues. From NMR experiments it was concluded that α-L-Fuc-(1→3)-β-D-GlcNAc and Lewis(x) bound to both lectins, whereas sialyl Lewis(x) only bound to AAA. Increased line broadening of 1H NMR signals of the carbohydrate ligands upon binding to AAA and LTL-A suggested that AAA bound to the ligands more tightly. Further comparison of line widths showed that for both lectins binding strengths decreased from α-L-Fuc-(1→3)-β-D-GlcNAc to Lewis(x) and were lowest for sialyl Lewis(x). Surface plasmon resonance measurements were then employed to yield accurate dissociation constants. TrNOESY, QUIET-trNOESY, and trROESY experiments delivered bioactive conformations of the carbohydrate ligands, and STD NMR experiments allowed a precise epitope mapping of the carbohydrates bound to the lectins. The bioactive conformation of Lewis(x) bound to LTL-A, or AAA revealed an unusual orientation of the fucose residue, with negative values for both dihedral angles, Φ and Ψ, at the α(1→3)-glycosidic linkage. A similar distortion of the fucose orientation was also observed for sialyl Lewis(x) bound to AAA. From STD NMR experiments it followed that only the L-fucose residues are in intimate contact with the protein. Presumably steric interactions are responsible for locking the sialic acid residue of sialyl Lewis(x) in one out of many orientations that are present in aqueous solution. The sialic acid residue of sialyl Lewis(x) bound to AAA adopts an orientation similar to that in the corresponding sialyl Lewis(x)/E-selectin complex.
Peer Reviewed Yes
Published Yes
Volume 123
Issue Number 43
Page from 10705
Page to 10714
ISSN 0002-7863
Date Accessioned 2007-11-13
Language en_AU
Research Centre Institute for Glycomics
Faculty Institute for Glycomics
Subject Biochemistry and Cell Biology; Enzymes; Medical Biochemistry: Carbohydrates
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1x

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