title: Mechanism of anticoagulant action by protein inhibitors from bovine testes and salmon sperm.
abstract: A protein inhibitor was isolated from commercial preparations of salmon sperm and its physical and anticoagulant properties were compared with an inhibitor isolated earlier from commercial preparation of bovine testicular hyaluronidase. The inhibitor from bovine source was heat and acid labile and had a molecular weight of approximately equal to 35000 while the one from salmon sperm had a molecular weight of approximately equal to 5700 and was stable to heat and acid. To determine the mechanism of the inhibitory effect, a system of purified components consisting of isolated prothrombin, Factor Xa, Factor Va, Ca++, and vesicles of phosphatidylcholine (PCPS, 25% PS) was used. Included also was dansylarginine N- (3-ethyl-1,5-pentanedidyl) amide (DAPA) which binds newly formed thrombin and yields the time course of prothrombin conversion by virtue of enhanced fluorescence of the DAPA - thrombin complex. The inhibitor of bovine testes was effective only when PCPS was the limiting component suggesting that its action was directed against the phospholipid component of the prothrombinase complex. The inhibitor from salmon sperm was found to lower the rate of conversion of prothrombin to thrombin in an in vitro system where thrombin generation was measured by its action on the chromogenic substrate H-D-Phe-Pip-Arg-pNa (S-2238). It inhibited the conversion of Factor X to Xa and also the the amidolytic cleavage by Factor Xa of chromogenic substrate N-Benz-Ile-Glu-Gly-Arg-pNa (S-2222).
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000302:isolation & purification; D001780:Blood Coagulation Tests; D002417:Cattle; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008970:Molecular Weight; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D012474:Salmon; D013094:Spermatozoa / Q000032:analysis*; D013737:Testis / Q000032:analysis*
chemical_list: D000925:Anticoagulants; D011506:Proteins