Alkali-Induced Optical Rotation Changes in Heparins and Heparan Sulfates, and Their Relation to Iduronic Acid-Containing Sequences

Under specific basic conditions, the glucosaminoglycans heparin and heparan sulfate, containing α-L-iduronic acid 2-O-sulfate, undergo selective epoxidation between C-2 and C-3 of this residue, with formation of a residue of 2,3-anhydro-α-L-guluronic acid. The epoxidation reaction was studied by means of 13C NMR and optical rotation measurements. The optical rotation values correlate well with the composition of the reaction products as determined by 13C NMR, thus indicating that the heparin- or heparan-like character of both natural and semisynthetic polysaccharides can be easily determined also through optical rotation measurements.