The role of diffusion in enzyme kinetics

Area of Science:

• Biochemistry
• Chemical Kinetics
• Physical Chemistry

Background:

• Enzyme kinetics are influenced by diffusion-controlled processes.
• Previous theory established a framework for bimolecular association/dissociation steps.

Purpose of the Study:

• To formulate criteria for the dependence of overall enzyme reaction rates on medium viscosity.
• To analyze the impact of enzyme adsorption onto colloidal particles on reaction rates and viscosity sensitivity.

Main Methods:

• Application of a rigorous theory for bimolecular association and dissociation.
• Development of criteria to assess the relationship between overall rate and medium viscosity.
• Theoretical consideration of enzyme immobilization on spherical colloidal particles.

Main Results:

• Established criteria indicate many enzymes show no significant rate dependence on medium viscosity, regardless of unmeasured rate constants.
• Enzyme adsorption onto larger colloidal particles does not increase reaction rates.
• Enzyme immobilization on colloidal particles can maintain or decrease reaction rates and maintain or increase viscosity sensitivity.

Conclusions:

• Diffusion is a critical factor in enzyme kinetics, with specific criteria predicting viscosity independence for many enzymes.
• Enzyme immobilization strategies require careful consideration of their impact on kinetics and diffusion limitations.
• The findings offer insights into enzyme behavior in various solution and immobilized states.