Heterogeneity in the composition of commercial heparins: Comparison of anticoagulant activities and biochemical compositions of anionic density-fractionated heparins

Abstract In this study the nature of compositional heterogeneity in commercial heparins was investigated. Five hog-mucosal (HM) and one beef-lung (BL) heparin were subjected to partition fraction in a two-phase system of 1-butanol containing hexadecylpyridinium chloride/aqueous NaCl, a system which fractionates heterogeneous heparins larger than 10,000 daltons according to anionic density. The heparins differed markedly in purity as determined by both the galactosamine content of the unfractionated preparations and the amount of uronate extracted at lower NaCl concentrations in the fractionation scheme. All fractions afforded linear plots of the logarithm of clotting time vs heparins concentration in the APTT assay with human plasma, thereby permitting measurement of concentration - independent specific activities. Equivalent fractions from different HM heparins had similar compositions, and with the exception of an unbleached sample, had equivalent specific APTT anticoagulant activities. These latter were linearly related to the square of anionic density. In contrast, the BL heparin behaved quite differently. Its most abundant fractions were extracted at higher NaCl concentrations than was the case for HM heparins, little systematic variation in anionic density was observed, and its fractions had much lower specific activities than equivalent HM fractions.