STRUCTURAL-ANALYSIS OF HEPARIN BY RAMAN-SPECTROSCOPY

The Raman spectra of commercially available heparin disaccharide stand ards exhibit bands associated with the N-sulfate and the 6-O-sulfate g roups of the glucosamine and the 2-O-sulfate of the iduronic acid. The N-sulfate has a strong band at 1039 cm(-1). The 6-O-sulfate and the 2 -O-sulfate exhibit bands at 1055 and 1065 cm(-1), respectively. The pa ttern of these modes, which are assigned to the symmetric SO3 vibratio ns, was supported by semiempirical quantum mechanical calculations. Th e above bands were identified in the Raman spectrum of a commercial pr eparation of porcine mucosal heparin and were used to determine the re lative proportion of the N-sulfate, 6-O-sulfate, and 2-O-sulfate group s in the heparin molecule. This information, which is complementary to that obtained by NMR spectroscopy, is of particular importance in rel ation to biological activity. This study also extends the usefulness o f Raman spectroscopy to include structural details required for the qu ality assurance of pharmaceutical preparations of heparin.