Inhibitory activities for thrombin and factor Xa of whale heparin: comparative studies on two preparations from...

Whale intestinal heparin preparations from Balaenoptera physalus L. (Bp) and Balaenoptera borealis L. (Bb) were fractionated by affinity chromatography on a column of antithrombin III (AT)-Sepharose 4B. The yields of high-affinity fractions for AT (HA) from Bp and Bb were 86.8 and 13.3%, respectively, in total. The inhibitory activities for thrombin of Bp and Bb and their HA and those for Factor Xa of the latter were compared in the presence of AT. The results indicated that the inhibitory activities for thrombin of Bp and its HA were higher than those of Bb and its HA, respectively. No noticeable difference in the inhibitory activity for Factor Xa was, however, observed between HA from Bp and Bb. The present observations confirm our previous assumption that the presence of the thrombin-binding regions in addition to the AT-binding regions in heparin molecule are essential for the manifestation of high inhibitory activity for thrombin in the presence of AT.