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Binding of human factor VIII to phospholipid vesicles
G E Gilbert1, B C Furie, B Furie
1Center for Hemostasis and Thrombosis Research, New England Medical Center, Boston, Massachusetts.
The Journal of Biological Chemistry
|January 15, 1990
Summary
Factor VIII, a key blood coagulation protein, binds to phospholipid membranes. This interaction, crucial for blood clotting, was quantified using biophysical techniques, revealing specific binding characteristics.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Factor VIII is a critical protein cofactor in blood coagulation.
- It significantly accelerates factor X activation by factor IXa on phospholipid surfaces.
- Understanding its membrane interactions is vital for comprehending hemostasis.
Purpose of the Study:
- To investigate the interaction of recombinant human factor VIII with phospholipid vesicles.
- To quantitatively characterize the binding kinetics and thermodynamics.
- To elucidate the role of phosphatidylserine in factor VIII binding.
Main Methods:
- Utilized gel filtration, rapid sedimentation, and resonance energy transfer (R.E.T.).
- Employed R.E.T. for quantitative equilibrium measurements of factor VIII binding to vesicles.
- Studied interactions with small and large unilamellar vesicles of varying phosphatidylserine content.
Main Results:
- Factor VIII demonstrated rapid and reversible binding to both small and large vesicles.
- Binding affinity (KD) was found to be as low as 2 nM, with specific phospholipid/protein ratios at saturation.
- Binding was dependent on phosphatidylserine mole fraction, exhibiting nonlinear behavior.
- Compared to factor V, factor VIII showed equivalent affinity but a higher phosphatidylserine requirement.
Conclusions:
- Factor VIII exhibits specific binding to phospholipid vesicles, influenced by phosphatidylserine content.
- A model was proposed to explain the nonlinear phosphatidylserine dependence of factor VIII binding.
- These findings provide insights into the molecular mechanisms of blood coagulation.