ENZYMES

Enzymes work under specific physico-chemical conditions, including temperature and pH (acid, basic or neutral medium), where their activity is optimal. Most proteins are degraded at 41°C (let's not forget that enzymes are proteins). They are then no longer functional. Moreover, the activity of enzymes can be slowed down or stopped by enzyme inhibitors.

It is possible to recognize an enzyme by its name, in particular thanks to the presence of the suffix « -ase », found for example in the term « amylase ».

They do not all have the same function. There are different classes (7 in total, referenced by the Enzyme Commission [EC]), characterised by the enzymatic reaction carried out:

Oxido-reductases

These enzymes perform oxidation-reduction reactions. They can degrade free radicals such as Super Oxide Dismutase (SOD) or generate them.

Transferases

They catalyse the transfer of a chemical group such as kinases, which add a phosphate group.

Hydrolases

They ensure the cleavage of bonds in the presence of water molecules (hydrolysis). These bonds may involve amino acids whose peptide bond is cleaved by prolyl-oligopeptidase and papain.

Glucoamylase, hemicellulase, invertase, pectinase and xylanase cleave the bonds involved in carbohydrates.

Lyases

Unlike hydrolases, these enzymes cleave bonds with reactions other than hydrolysis. One example is decarboxylases, which break carbon-carbon bonds.

Isomerases

These enzymes carry out isomerisation reactions, i.e. the rearrangement of functional groups within a molecule.

Ligases

These enzymes create bonds between two molecules. This is particularly the case with enzymes used in molecular biology.