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Functional domains of rabbit thrombomodulin
Summary
Thrombomodulin, a protein involved in blood clotting, has two forms. The acidic form contains a heparin-like substance responsible for anticoagulant activity and protein C activation, separable by proteinase.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Thrombomodulin is a crucial protein in regulating blood coagulation.
- It plays a key role in activating protein C, a natural anticoagulant.
Purpose of the Study:
- To characterize the different functional domains of thrombomodulin.
- To investigate the molecular basis of thrombomodulin's anticoagulant activities.
Main Methods:
- Ion-exchange chromatography and density-gradient centrifugation were used to separate thrombomodulin fractions.
- Enzymatic digestion with bacterial heparinase and NaDodSO4/PAGE were employed for further analysis.
Main Results:
- Thrombomodulin fractions were separated based on charge and molecular weight.
- An acidic fraction exhibited direct anticoagulant activity and accelerated thrombin inhibition by antithrombin, linked to a heparin-like polysaccharide.
- This acidic component, associated with a higher molecular weight form (68,000 Mr), could be separated from the protein C activation cofactor.
Conclusions:
- Thrombomodulin's anticoagulant properties are attributed to an associated heparin-like polysaccharide.
- This polysaccharide moiety is separable from the protein C activation site by proteinase activity.
- The findings elucidate the structural basis for thrombomodulin's diverse functions in hemostasis.