The Structure of Cellulose by Conformational Analysis.

Abstract

Conformational analysis studies on the tertiary structure of cellobiose and methyl-β-cellobioside were carried out by using calculations of Van der Waals, H-bond, electrostatic and torsional energy interactions between the atoms and groups of the molecules. Energy maps in function of the rotational angles ψ° and φ° of the glucosidic bond were obtained in increments of 20° and refined in increments of 1°. Two “primary” and one “secondary” conformations of minimum energy were obtained for both cellobiose and methyl-β cellobioside, some of which are equivalent to results obtained by X-ray diffraction. The H-bond forces were shown to be, together with the Van der Waals forces, the predominant factor in the fixation of the conformations of minimum energy. The position and energy contributions of the H-bond patterns for the favoured conformations were identified.