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An assay to quantify the two plasma isoforms of factor V
1Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
Thrombosis and Haemostasis
|January 12, 2001
Summary
This study presents a novel assay to quantify blood coagulation factor V (FV) forms FV1 and FV2. The assay helps understand the FV1/FV2 ratio shift in carriers of the R2 haplotype, linked to thrombosis risk.
Area of Science:
- Hematology
- Biochemistry
- Molecular Biology
Background:
- Blood coagulation factor V (FV) exists in two forms, FV1 and FV2.
- FV1 is more thrombogenic than FV2 in purified systems.
- The R2 haplotype polymorphism in FV is associated with increased thrombosis risk and a shift towards the thrombogenic FV1 form.
Purpose of the Study:
- To describe a detailed assay for quantifying plasma levels of FV1 and FV2.
- To enable the measurement of the FV1/FV2 ratio in plasma.
- To investigate the implications of the FV1/FV2 ratio in thrombosis risk.
Main Methods:
- FV in diluted plasma was activated to FVa using thrombin.
- FVa was quantified using two distinct prothrombinase-based assay systems.
- Differential cofactor activity of FVa1 and FVa2 under varying substrate concentrations was exploited.
Main Results:
- One assay quantified total FV (FV1 + FV2) at saturating conditions.
- A second assay, under suboptimal conditions, revealed an 8-fold higher activity for FVa2 compared to FVa1, allowing relative quantification.
- Calibration curves enabled calculation of absolute FV1 and FV2 concentrations in plasma.
Conclusions:
- A reliable method for quantifying plasma FV1 and FV2 levels has been established.
- This assay facilitates the study of FV1/FV2 ratio variations in relation to thrombotic risk.
- Understanding FV isoform distribution is crucial for assessing individual thrombosis predisposition.