The isolation of l-iduronic acid from the crystalline barium acid salt of heparin

Abstract

The thrice-recrystallized barium acid salt of heparin was hydrolyzed by a modified Monier-Williams method with 72% sulfuric acid at 25°, followed by dilution and refluxing. The uronic acid fraction (13%) of the hydrolyzate was chromatographically shown to contain d-glucuronic acid, l-iduronic acid, and their lactones. The l-iduronolactone component was isolated, and characterized as the crystalline brucinium salt of its acid. It was established that the l-iduronic acid was derived neither from contaminant dermatan sulfate nor through C-5 epimerization of d-glucuronic acid. Previous hydrolytic conditions (which gave, in addition to 2-amino-2-deoxy- d-glucose, only d-glucuronic acid or d-glucose from purified heparin or its partially carboxyl-reduced derivatives, respectively) are now considered to have been too drastic to give all of the representative, degradation fragments.