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Hot Biological Catalysis: Isothermal Titration Calorimetry to Characterize Enzymatic Reactions
Published on: April 4, 2014
Relations between biochemical thermodynamics and biochemical kinetics
1Department of Chemistry, Massachusetts Institute of Technology, Room 6-215, MIT, 77 Mass. Ave., Cambridge, MA 02139, USA. alberty@mit.edu
Biophysical Chemistry
|June 13, 2006
Summary
Enzyme kinetics parameters are influenced by environmental factors, but the overall reaction equilibrium and composition remain independent of these specific enzyme site properties. This study explores the relationship between enzyme kinetics and equilibrium in catalyzed reactions.
Area of Science:
- Biochemistry
- Enzyme Kinetics
- Chemical Thermodynamics
Background:
- Enzyme-catalyzed reaction rate parameters are sensitive to temperature, pH, and ionic strength.
- These parameters can also be affected by buffer species concentrations.
- Complete rate equations describe both forward and reverse reaction kinetics.
Purpose of the Study:
- To investigate the relationship between kinetic parameters and the apparent equilibrium constant in enzyme catalysis.
- To demonstrate how equilibrium composition can be derived from kinetic data.
- To analyze the cancellation of environmental effects (pH, ionic strength) in Haldane relations.
Main Methods:
- Determination of complete rate equations for enzyme-catalyzed reactions.
- Application of Haldane relations connecting kinetic parameters and equilibrium constants.
- Analysis of simple enzymatic mechanisms and their rate equations.
Main Results:
- Haldane relations establish a link between kinetic parameters and the apparent equilibrium constant.
- The apparent equilibrium constant and resulting equilibrium composition are independent of enzyme site properties.
- Environmental effects on enzyme sites must cancel out in Haldane relations or equilibrium calculations.
Conclusions:
- Despite environmental dependencies of kinetic parameters, enzyme-catalyzed reaction equilibrium is predictable from kinetics.
- The independence of equilibrium composition from specific enzyme site properties is a key finding.
- Understanding these relationships is crucial for accurately modeling enzyme function under varying conditions.
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