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Medium effects on the kinetics of human plasmin
1Abbott Laboratories, Thrombolytics Venture Discovery, Abbott Park, IL 60064.
Thrombosis Research
|February 1, 1992
Summary
Organic solvents significantly alter serine proteinase activity, especially plasmin. Solvent hydrophobicity impacts plasmin
Area of Science:
- Biochemistry
- Enzymology
- Protease research
Background:
- Serine proteinases are crucial enzymes in biological processes.
- Understanding enzyme activity in varied solvent environments is key for biochemical research and drug development.
- Organic solvents are often used in biochemical assays but can affect enzyme kinetics.
Purpose of the Study:
- To investigate the impact of water-miscible organic solvents on serine proteinase activity.
- To elucidate the relationship between solvent hydrophobicity and plasmin enzyme kinetics.
- To explore substrate-specific effects on plasmin activity in mixed solvent systems.
Main Methods:
- Assaying the activity of several serine proteinases in aqueous buffers containing varying concentrations of water-miscible organic solvents.
- Characterizing kinetic parameters (Km and kcat) of plasmin using chromogenic substrates like H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and pro-urokinase.
- Analyzing the correlation between solvent polarity and enzyme activity (log (kcat/Km)).
Main Results:
- Plasmin activity demonstrated significant alterations based on the hydrophobicity of the organic solvent.
- An inverse linear correlation was found between mixed solvent polarity and the log (kcat/Km) of plasmin activity for specific substrates.
- Plasmin's activity showed reduced dependence on solvent polarity when using chromogenic substrates with an arginyl residue at the P1 site.
Conclusions:
- The hydrophobicity of organic solvents critically modulates serine proteinase activity, particularly for plasmin.
- Solvent polarity is a key determinant of plasmin's catalytic efficiency (kcat/Km) with certain substrates.
- Substrate design influences the sensitivity of plasmin activity to changes in the solvent environment.
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