Characterization of chemically crosslinked human factor VIIIa

Area of Science:

• Biochemistry
• Hematology
• Protein Chemistry

Background:

• Factor VIIIa is a critical procoagulant enzyme in the blood coagulation cascade.
• The intrinsic instability and limited activity of native factor VIIIa pose challenges in therapeutic applications.
• Understanding factor VIIIa structure-function relationships is crucial for developing improved hemostatic agents.

Purpose of the Study:

• To investigate the effect of chemical crosslinking on factor VIIIa activity and stability.
• To characterize the structural modifications and functional properties of crosslinked factor VIIIa.
• To explore the potential of crosslinking for enhancing factor VIIIa therapeutic efficacy.

Main Methods:

• Treatment of factor VIII with the crosslinker disuccinimidyl suberate.
• Purification of crosslinked factor VIIIa using immunoaffinity chromatography and gel filtration.
• Electrophoretic analysis (SDS-PAGE) and fractionation using immobilized von Willebrand factor.
• Assessment of factor VIIIa activity and stability under defined conditions (4°C, pH 7.2).

Main Results:

• Crosslinking factor VIII with disuccinimidyl suberate resulted in >200-fold enhanced factor VIIIa activity compared to native factor VIIIa.
• The crosslinked factor VIIIa exhibited remarkable stability, remaining active for at least 15 days at 4°C and pH 7.2.
• Electrophoresis indicated the formation of high-molecular-mass species and stabilization through intra- and/or inter-subunit crosslinks.
• Fractionation revealed that factor VIIIa activity was associated with trimers containing intra-subunit crosslinks.

Conclusions:

• Chemical crosslinking is an effective strategy to significantly enhance the activity and stability of factor VIIIa.
• Crosslinked factor VIIIa, particularly intra-subunit crosslinked trimers, represents a more robust and potentially therapeutic form of the enzyme.
• Further investigation into the specific crosslinking sites and their impact on thrombin cleavage (e.g., at arginine 372) is warranted.