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CA-1 method, a novel assay for quantification of normal prothrombin using a Ca2+ -dependent prothrombin activator,
1Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan.
Thrombosis Research
|May 21, 1999
Summary
A new CA-1 method quantifies normal prothrombin using a snake venom activator. This rapid assay accurately monitors coagulant activity in warfarin patients.
Area of Science:
- Biochemistry
- Hematology
- Assay Development
Background:
- Prothrombin is a crucial vitamin K-dependent protein in the coagulation cascade.
- Accurate monitoring of prothrombin levels is essential, particularly in patients on anticoagulant therapy like warfarin.
- Existing assays may have limitations in sensitivity, speed, or interference from common anticoagulants.
Purpose of the Study:
- To establish and validate a novel chromogenic microplate assay (CA-1 method) for quantifying normal prothrombin.
- To assess the utility of the CA-1 method for monitoring coagulant activity in warfarin-treated individuals.
- To evaluate the assay's performance characteristics, including sensitivity, speed, and resistance to inhibitors.
Main Methods:
- Developed a prothrombin assay (CA-1 method) utilizing carinactivase-1 (CA-1), a Ca2+-dependent activator from Echis carinatus leucogaster venom.
- Employed a specific chromogenic substrate (t-butoxy-Val-Pro-Arg-p-nitroanilide) cleaved by thrombin generated from prothrombin.
- Measured the velocity of p-nitroaniline liberation to determine normal prothrombin levels in plasma samples.
Main Results:
- The CA-1 method demonstrated high correlation with traditional coagulation assays (prothrombin time and thrombotest) in warfarin-treated patients.
- The assay is rapid, highly sensitive, and effective for quantifying normal prothrombin in the range of 10-200 ng/100 microl.
- Normal prothrombin levels measured by the CA-1 method were unaffected by EDTA and heparin, unlike conventional tests.
Conclusions:
- The CA-1 method provides a novel, sensitive, and rapid chromogenic assay for normal prothrombin quantification.
- This assay is suitable for high-throughput analysis and effective for monitoring coagulant activity in warfarin-treated individuals.
- The CA-1 method offers an advantage over existing assays due to its independence from heparin and EDTA inhibition.