A diffusion Michaelis-Menten mechanism: continuous conformational change in enzymatic kinetics

Area of Science:

• Biochemistry
• Enzymology
• Chemical Kinetics

Background:

• The Michaelis-Menten mechanism is a cornerstone of enzyme kinetics.
• Understanding enzyme conformational changes is crucial for elucidating catalytic mechanisms.
• Existing models may not fully capture the dynamic nature of enzyme active sites.

Purpose of the Study:

• To develop a model that quantitatively describes enzymatic catalysis with continuous protein conformational changes.
• To explore the relationship between solvent viscosity and enzyme activity within this new framework.
• To propose solvent viscosity as an experimental probe for conformational change mechanisms.

Main Methods:

• Development of a theoretical model extending the Michaelis-Menten mechanism.
• Incorporation of continuous protein conformational dynamics into the model.
• Analysis of steady-state kinetics and dependence on solvent viscosity.

Main Results:

• The model yields a Michaelis-Menten-like equation under steady-state conditions.
• The catalytic step demonstrates significant dependence on solvent viscosity.
• The model provides a quantitative representation of "rack" or "induced fit" mechanisms.

Conclusions:

• Continuous protein conformational change is a viable addition to enzymatic catalysis models.
• Enzyme activity's sensitivity to solvent viscosity can indicate conformational dynamics.
• Investigating viscosity effects offers a potential experimental validation for conformational change hypotheses in enzymes.