Molecular conformation of sodium heparan sulphate in the condensed phase

Abstract
By using the X-ray-diffraction results reported previously for sodium heparan sulfate, a 2-fold helical conformation with an axially projected disaccharide repeat (h) equal to 0.93 nm was examined in detail. On the basis of a repeating sequence of 1,4-.alpha.-D-glucosamine and 1,4-.beta.-D-glucuronic acid, trial and stereochemically feasible molecular models were computer-generated. An optimum 2-fold helical conformation is proposed, incorporating stabilizing intra-chain H-bonds across both glycosidic linkages.