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Activation of 125 I‐Factor IX and 125 I‐Factor X: Effect of Tissue Factor and Factor VII, Factor X a and Thrombin
Author(s) -
ØSterud Bjarne,
Rapaport Samuel I.
Publication year - 1980
Publication title -
scandinavian journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0036-553X
DOI - 10.1111/j.1600-0609.1980.tb01329.x
Subject(s) - tissue factor , factor ix , factor x , chemistry , factor vii , cleavage (geology) , thrombin , factor ixa , factor v , biochemistry , medicine , platelet , coagulation , biology , immunology , paleontology , thrombosis , fracture (geology)
Activation of Factor IX and Factor X was studied by adding 125 I‐Factor IX or 125 I‐Factor X to reaction mixtures and quantitating cleavage products by reduced sodium dodecylsulfate gel electrophoresis. Thrombin failed to activate Factors IX or X; Factor X a produced insignificant amounts of cleavage products of both factors. In contrast, the reaction product of tissue factor and Factor VII cleaved large amounts of both Factor IX and Factor X in purified systems and in plasma. In incubation mixtures of plasma containing added 125 I‐Factor IX or 125 I‐Factor X, tissue factor and Ca2+ions, the percentage of total radioactivity in the heavy chain peak of 125 I‐IX a and the heavy chain peak of 125 I‐X a increased at a similar rate. When the tissue factor was diluted, similar curves were obtained for percent cleavage of 125 I‐Factor IX and percent cleavage of 125 I‐Factor X plotted against tissue factor concentration. These findings support the hypothesis that activation of Facor IX by the tissue factor‐Factor VII reaction product represents a physiologically significant step in normal haemostasis.