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Tryptase from rat mast cells converts bovine prothrombin to thrombin
Biochemical and Biophysical Research Communications
|October 30, 1985
Summary
Rat mast cell tryptase activates bovine prothrombin, generating thrombin activity. This activation process is similar to factor Xa but forms a unique intermediate, highlighting tryptase
Area of Science:
- Biochemistry
- Enzymology
- Hematology
Background:
- Mast cells play a role in inflammatory and hemostatic processes.
- Prothrombin is a key zymogen in the coagulation cascade, essential for thrombin generation.
Purpose of the Study:
- To investigate the enzymatic activity of rat mast cell tryptase on bovine prothrombin.
- To characterize the mechanism and kinetics of prothrombin activation by tryptase.
Main Methods:
- Purification of tryptase from rat peritoneal mast cells.
- Assay of thrombin activity using a synthetic substrate (t-butyloxy-carbonyl-Val-Pro-Arg-4-methylcoumaryl-7-amide).
- Kinetic analysis (Km, kcat) and SDS-PAGE to analyze activation products and time course.
Main Results:
- Rat mast cell tryptase demonstrated prothrombin-activating capacity, leading to increased thrombin activity.
- Kinetic parameters for tryptase activation of prothrombin were determined (Km = 2.3 µM, kcat = 46.3 s⁻¹).
- Prothrombin activation by tryptase followed a pathway similar to activated factor X (Xa), with the notable formation of a 67 kDa intermediate.
Conclusions:
- Rat mast cell tryptase is a potent activator of bovine prothrombin.
- Tryptase-mediated prothrombin activation shares mechanistic similarities with factor Xa but involves a distinct intermediate, suggesting unique enzymatic properties.