Molecular modeling of a disialylated monofucosylated biantennary glycan of the N-acetyllactosamine type.

The conformations of a disialylated monofucosylated biantennary glycan of the N-acetyllactosamine type were analysed using the Tripos 5.3 force field from the Sybyl software currently used for molecular modelling. The conformation of each glycosidic linkage was calculated when included in oligosaccharide structures of up to 5 units and the influence of the glycosidic environment on the overall structure was measured. The study clearly shows that the conformation of a branched glycan cannot result from the simple addition of the different low energy conformers of each of the glycosidic linkages constituting the glycan structure. The asymmetrical conformation of the two antennae was demonstrated. The lowest energy conformations of the overall glycan structure were built and classified into 5 main models: the Y, T, bird and broken wing conformations already described and a new one called the 'back folded wing conformation.'