PURPOSE: To measure the biological activity of antithrombin III with high reliability and reproducibility, by measuring the amount of produced p-nitroanilide using thrombin and D-phenyl-prolylarginyl-p-nitroanilide.
CONSTITUTION: The amount of p-nitroaniline liberated by the enzymic reaction of thrombin with D-phenyl-prolyl-arginyl-p-nitroanilide in a specimen blood plasma is measured by the colorimetry. The enzymic reaction with the D-phenyl- prolyl-arginyl-p-nitroanilide is carried out in a standard blood plasma and a buffer solution prepared respectively to give 100% thrombin activity in place of the blood plasma as a control to measure the amount of the p-nitroaniline which is a liberation product. The activity of the antithrombin III in the specimen blood plasma is obtained as a relative ratio to the standard activity from the formula putting the antithrombin III activity by the standard blood plasma as 100%.
ANAI IZUMI
KAWAGUCHI YOSHIHIRO
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