A novel method for differentiating dextran sulfate from related sulfated polysaccharides

A method is described for unequivocal identification of dextran sulfate, based on combined chemical desulfation and dextranase enzymolysis of dextran sulfate moieties to isomaltose, a specific indicator of dextran-type precursors. The method was developed using high-resolution (300 MHz) 1H NMR spectroscopy for assurance of the molecular transformations, identification, and estimation of the hydrolysis products. Overall conversion of approximately 80% of highly sulfated and moderately sulfated dextran sulfates was realized. Both 2-D 1H and 13C NMR spectra of a dextran sulfate (MW 500,000) clarified the extent of sulfation (75%) at C-4 and confirmed that sulfation at positions C-2 and C-3 was virtually complete. Estimation of the hydrolysis products (isomaltose, major; alpha-D-glucose, minor) is not restricted to 1H NMR now that the desulfation-enzymolysis methodology has been established; rather, it can be performed using HPLC or GLC (with derivatization).