Criteria of choice of the helix type in crystalline dextran

A reduction in the water content in dextran samples crystallized from water-salt solution results in transformation of the crystal lattice of the polymer-salt complex due to stretching of the polysaccharide chains. A right helix of the 52 type has been selected as the most preferential for crystalline dextran on the basis of energy, thermodynamic and crystallographic criteria. It is concluded that maximally stretched helices with the lowest (for the theoretically possible isoenergic conformers) symmetry and a minimal diameter are realized in polysaccharide crystals.