Weak Calcium-Mediated Interactions between Lewis X-Related Trisaccharides Studied by NMR Measurements of Residual Dipolar Couplings

Abstract

The Lewis X (LeX) determinant, a trisaccharide with the carbohydrate sequence Galbeta(1-->4)[Fucalpha(1-->3)]GlcNAcbeta, is believed to be responsible for Ca2+-mediated cell-cell interactions. In partly oriented phases composed of mixtures of penta(ethyleneglycol)monododecyl ether HO(CH2CH2O)5C12H25 and n-hexanol in the presence of Ca2+ ions, the variation of the residual dipolar couplings 1DCH of various CiHi vectors in LeX as a function of the concentration of the trisaccharide demonstrates the existence of very weak LeX-Ca2+-LeX complexes in solution. Synthetic 3-, 4-, and 6-deoxy-LeX variants were also shown to form complexes in the presence of calcium ions, despite the replacement of one of their hydroxyl groups by hydrogen atoms. This is the first direct observation in solution of a calcium-mediated interaction between LeX molecules.

Molecular dynamics simulations and NMR spectroscopy studies of trehalose–lipid bilayer systems

“…In the isotropic liquid only the J-couplings are observable, whereas the direct dipolar interactions are averaged (by the rapid molecular tumbling) to zero. [44][45][46][47][48][49][50][51] We have used trajectories generated in the MD simulations carried out in the previous study 5 for interpretation of experimental herein acquired NMR parameters and analyses of the membrane-TRH interactions. In principle, there are two NMR spectroscopy techniques to study anisotropic dipolar interactions: a) conventional high-resolution NMR where a weakly ordered solvent [37][38][39] is used, and b) solid-state NMR.…”

Random‐Coil:α‐Helix Equilibria as a Reporter for the LewisX–LewisX Interaction

“…[7] These studies have generally (though not exclusively) focused on the biologically important Lewis X -Lewis X (Le X -Le X ) interaction. [4][5][6][7][8] As a result, a number of factors important in CCIs are now apparent, and these include multivalent (Velcro-like) presentation of carbohydrates on a surface; a requirement for polyamphiphilic surfaces associated with the hydraphobic effect; [9] and, in certain cases, roles for both divalent metal cations (e.g. Ca 2+ ) and ionic (charge) effects.…”

Synthesis of 3″- and 4″-deoxy-Lewisx trisaccharides: A useful tool for study of carbohydrate-carbohydrate interaction

“…Rat basophilic leukaemia cells pre-incubated with purified Le x -containing glycosphingolipids have also been used as a model [18]. Recently we reported an experimental strategy to characterize weak Le x /Ca 2+ /Le x interaction by NMR measurements of residual dipolar coupling, providing an unequivocal evidence of the existence of Le x -Ca 2+ -Le x complexes in solution, this is the first direct observation in solution of a calcium-mediated interaction between Le x molecules [19]. In an effort to better understand the formation of such complexes, several variants of Le x were investigated, for example, synthetic 4″-and 3″-deoxy-Le x trisaccharides (compounds 1 and 2) were also shown to form complexes in the presence of calcium ions, despite the replacement of one of their hydroxyl groups by hydrogen atoms.…”