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Prothrombin activation in rabbits
D Seiffert1, T J Mitchell, Z Wang
1Department of Chemical Enzymology, DuPont Pharmaceuticals Company, Wilmington, Delaware, USA. Seiffert@dupont.pharma.com
Thrombosis Research
|February 25, 1999
Summary
Rabbit prothrombin activation fragment F 1.2 is not a reliable marker for coagulation activation. Differences in factor Xa cleavage sites, not cofactors, explain variations in human versus rabbit prothrombin activation.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Prothrombin activation fragment F 1.2 (F 1.2) is a marker for coagulation system activation.
- Previous studies have primarily focused on human prothrombin activation.
Purpose of the Study:
- To evaluate rabbit prothrombin activation fragment F 1.2 (F 1.2) as a marker for coagulation activation.
- To investigate the molecular basis for differences in prothrombin activation between rabbits and humans.
Main Methods:
- Development of a competitive F 1.2 ELISA using monoclonal antibodies against rabbit F 1.2.
- Immunoblotting analysis of endogenous and labeled prothrombin.
- cDNA sequencing of rabbit prothrombin.
Main Results:
- Rabbit plasma showed no detectable F 1.2 increase upon recalcification, unlike human plasma.
- Rabbit serum contained meizothrombin and thrombin B-chain, but not F 1.2, differing from human serum.
- Rabbit F 1.2 formation was observed with purified components, suggesting altered factor Xa cleavage susceptibility.
Conclusions:
- Rabbit F 1.2 is not a suitable marker for coagulation activation in rabbits.
- A six amino acid deletion near the 271/272 site in rabbit prothrombin likely reduces factor Xa cleavage efficiency compared to humans.
- Differences in prothrombin structure, specifically factor Xa cleavage sites, explain species-specific activation patterns.