mm3 Potential energy surfaces of trisaccharide models of λ-, μ-, and ν-carrageenans

The adiabatic potential energy surfaces (PES) of six trisaccharides, sulfated derivatives of α-d-Galp-(1→3)-β-d-Galp-(1→4)-α-d-Galp and β-d-Galp-(1→4)-α-d-Galp-(1→3)-β-d-Galp representing models of λ-, μ-, and ν-carrageenans were obtained using the mm3 force-field at ε = 3. Each PES was described by a single contour map for which the energy is plotted against the two ψ glycosidic angles, given the small variations of the ϕ glycosidic torsional angle in the low-energy regions of disaccharide maps. Most surfaces appear as expected from the maps of the disaccharidic repeating units of carrageenans, with less important factors altering the additive effect of both linkages. Only small interactions between the first and third monosaccharidic moieties of the trisaccharides are observed. The flexibility of the α-linkages appears nearly identical to that in their disaccharide counterparts, with only one exception, where it appears reduced by the presence of the third monosaccharide. On the other hand, the flexibility of the β-linkage appears to be equal or sometimes even higher than that observed for the corresponding disaccharide.

Figure optionsDownload as PowerPoint slide