Abstract: A potent and specific inhibitor of thrombin is purified from salivary gland extracts of the tsetse fly, Glossina morsitans morsitans. The inhibitor has a molecular weight of 3530 Daltons as determined by laser desorption mass spectroscopy. The inhibitor is useful as an anticoagulant and an inhibitor of platelet aggregation and in pharmaceutical and immunogenic compositions.

Abstract: A soluble anticoagulant protein isolated and purified from Ancylostoma hookworms markedly prolongs both the prothrombin time and partial thromboplastin time in clotting assays. The protein has an apparent molecular weight of about 6500 daltons and exhibits amino acid sequence homology to the Kunitz-type serine protease inhibitor family. Chromogenic peptide substrate and clotting time assays indicate that the protein inhibits extrinsic pathway clotting factor VIIa, the enzyme responsible for initiating the human coagulation cascade, and factor Xa in the common pathway of the coagulation cascade.