The uronic acid composition of anticoagulantly active and inactive heparin

Bovine heparin was fractionated with respect to chain length and anticoagulant activity. Analysis of each of these fractions for iduronic and glucuronic acids demonstrated that active heparin has a greater amount of glucuronic acid than inactive heparin. The ratio of the uronic acids in the respective fractions was the same for heparin with different molecular weights. Thus, active heparin with longer chain lengths have more additional glucuronate residues than are required for the antithrombin-binding domain. The results indicate that the active and inactive heparin species differ in more than one structural characteristic and suggest a considerable divergence in their respective biosynthesis.