Molecular enzymology - Enzymatic catalysis

Enzymes are biochemical catalysts with similarities to chemical catalysts.

An enzyme is the gas pedal of a specific chemical reaction at a given temperature and pH. The accelerating factor is generally between 10 ⁵ and 10 ⁸ . The enzymatic reaction is specific and its action takes place at low concentration without denaturation ensuing. The reaction equilibrium is not altered and is reached rapidly in correlation with the accelerating factor previously discussed. These characteristics make these macromolecules indispensable to cell metabolism and its regulation.

The enzyme differs from a chemical catalyst in that its protein nature makes it sensitive to physicochemical conditions that are not compatible with the environments found in living beings. It is also active at low concentrations, which can lead to saturation by the reagents it needs to transform.

This catalytic aspect of enzymology is of particular interest when using enzymatic reactors, where an enzyme is immobilized on a solid support in order to carry out a specific chemical reaction on a large, or even very large, scale. Data on enzymatic kinetics, and the flow of substrates, products and other molecules required for the reaction within the reactors are all parameters that need to be studied with precision. Reactors can be used for chemical reactions, pharmaceutical preparations, cosmetics and food processing. More recently, these applications are being carried out using enzymatic membrane reactors. The enzyme is bound to the membrane surface or located in its pores. The reaction takes place when the substrate crosses the membrane.

Knowing the structure and function of an enzyme enables you to exploit this biological catalyst in the best possible conditions, with a view to optimizing its use in various industrial fields. Numerous catalysts (glycosidases, proteases, lipases...) are studied and used in reactors to produce a variety of high value-added molecules. For example, the flavor production market is worth several billion euros a year. It depends on enzymes operating in yeast, bacteria or plant cells in fermenters (lactone synthesis, etc.), or on purified enzymes immobilized or not in reactors (synthesis of hexanal, hexenal, fatty acid esters, etc.). What's more, in the pharmaceutical industry, enzymes provide access to intermediates and/or chiral drugs in a single step, offering a significant economic and ecological gain compared to their access requiring multi-step synthesis.

At the end of the article, readers will find a glossary and a table of notations and symbols used.