Activated factor X inhibitor in macroglobulin.

Draculin, the anticoagulant factor in vampire bat saliva, is a tight-binding, noncompetitive inhibitor of activated factor X.

The kinetic mechanism of action of Draculin on activated Factor X (FXa) is established. Draculin inhibits activated Factor X within seconds of incubation at near equimolar concentration (2-6 times on molar basis). Fitting the data to the equation for a tight-binding inhibitor gives a value for K(i)(K(d)) = 14.8+/-1.5 nM. The formation of the Draculin-FXa complex can be explained by a two-step m...

Rabbit plasma inhibitor of the activated species of blood coagulation factor X. Purification and some properties.

A naturally occurring inhibitor of activated blood coagulation Factor X has been isolated from pooled rabbit plasma and purified by the combination of Sephadex G-ZOO gel filtration, DEAE-Sephadex A-SO, and DEAE-cellulose chromatography. On microzone electrophoresis the purified product traveled as an az-globulin, and on 7.5% polyacrylamide gel disc electrophoresis at pH 9.5 it traveled as a sin...

Titration of activated bovine Factor X.

p-Nitrophenyl-p’-guanidinobenzoate is a suitable substrate for the titration of purified bovine Factor X which has been activated by a coagulant protein from Russell’s viper venom. Reaction of Factor Xa with p-nitrophenyl-P’-guanidinobenzoate occurs at the site which is responsible for the clotting activity of Factor Xa. Activation of bovine Factor X by the Russell’s viper venom coagulant prote...

Bovine Thrombin and Activated Factor X

Parke-Davis bovine thrombin was resolved into three distinct protein peaks on a Sephadex G-200 column. A stepwise chromatographic technique on diethylaminoethyl (DEAE) cellulose was developed for the complete separation and partial purification of thrombin and activated Factor X. Thrombin was quantitatively eluted in the first protein peak with 0.1 M NaCl, pH 7.0. A second peak with residual th...

FIRST SURVEY OF FACTOR IX INHIBITOR IN NORTHEASTERN IRAN