CONFORMATION OF THE GLYCOLIPID GLOBOSIDE HEAD GROUP IN VARIOUS SOLVENTS AND IN THE MICELLE-BOUND STATE

The three-dimensional (3D) structure of the oligosaccharide part of the globotetraosylceramide (globoside), GalN Acβ1-3Galα1-4Galβ1-4Glcβ1-1 Cer, was modeled in Me2SO and Me2NCHO solutions with use of a distance mapping procedure, which involved NOE contacts between the amido, hydroxy, and C-linked protons. The oligosaccharide chain showed a pronounced flexibility of each of the glycosidic linkages, while preserving a global “L” shape. A similar conformation was found for globoside anchored in mixed dodecylphosphocholin micelles in D2O solution, where it experiences a fast internal rotation on a time scale of 0.4 ns. It was concluded that the hard-sphere exo-anomeric (HSEA) model applied elsewhere did not predict correctly the 3D structure of globoside, while molecular mechanics calculations, used extensively in the present work, approach more closely the true oligosaccharide conformations. © 1990, American Chemical Society. All rights reserved.