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Electrostatic effects in trypsin reactions. Influence of salts
1Institute of Chemical Physics and Biophysics, Estonian Academy of Sciences, Tallinn.
European Journal of Biochemistry
|June 1, 1994
Summary
Inorganic salts influence trypsin activity by acting as competitive inhibitors for cationic substrates. Enzyme modifications, like adding negative charges, can enhance trypsin
Area of Science:
- Biochemistry
- Enzymology
- Protein Chemistry
Background:
- Trypsin is a key serine protease involved in various biological processes.
- Understanding the factors influencing trypsin activity is crucial for its applications in research and industry.
Purpose of the Study:
- To investigate the impact of inorganic salts on trypsin-catalyzed reactions.
- To elucidate the mechanisms underlying salt effects on substrate binding and enzyme kinetics.
- To explore strategies for modulating trypsin's catalytic properties.
Main Methods:
- Enzyme kinetics assays were performed to measure trypsin activity.
- The effects of various inorganic salts on substrate hydrolysis were analyzed.
- Chemical modification of trypsin was employed to alter its properties.
Main Results:
- Monovalent cations act as reversible competitive inhibitors for cationic substrates but not neutral ones.
- A non-electrostatic salt effect, attributed to substrate activity coefficients, influences binding.
- Trypsin active-site acylation rates are unaffected by monovalent cation salts.
- Chemical modification of lysine residues enhanced trypsin's specificity for cationic substrates.
Conclusions:
- Substrate binding involves extraction into an enzyme microphase, limiting external access.
- A dipole interaction between substrate cationic groups and Asp189 is key for acylation.
- Lysine residues are potential targets for site-directed mutagenesis to improve trypsin's selectivity and catalytic efficiency.