INTRODUCTION TO IMMOBILIZED ENZYME KINETICS

The kinetics of immobilized enzyme reactions are influenced by a variety of factors:

• Mass transfer resistances
• Possible reactions between support and the enzyme.
• Micro-environmental conditions.

Effect of Mass transfer resistances on Immobilized Enzyme Kinetics: (Mass transfer- Catalytic Reaction coupling)
Mass transfer resistances play a very important role in determining the immobilized enzyme kinetics.
The Substrate has to cross the film above the solid support and then diffuse through the matrix to the enzyme molecule embedded in the matrix. So, the enzyme will have to encounter two mass transfer resistances :

1. External Mass transfer Resistance encountered while passing through the film.
2. Internal Mass transfer Resistance encountered while diffusing through the matrix.

Possible reactions between support and the enzyme
A proper choice has to be made while selecting a support for the immobilization of the enzyme. The chemical nature of the support material and any possible reactions between the support and the enzyme should be taken into account. The reaction between support and the enzyme causes chemical modifications within the enzyme. These are called conformational effects.

Micro-environmental conditions
Micro-environmental conditions like pH, temperature and the ionic environment with in the immobilized enzyme particle influence the immobilized enzyme kinetics.

Thus immobilization may alter the intrinsic properties of the enzyme. Some times entirely different rate constants and entirely different equations should be used to characterize the immobilized enzyme kinetics.