How Are Enzymes Classified?

Enzymes may be classified according to the chemical reactions they catalyse. Digestion is an example of a simple chemical reaction called hydrolysis (hydro=water lysis=splitting). In hydrolysis, water molecules are needed to break down a complex molecule into simpler molecules. Therefore enzymes that catalyse hydrolytic reactions are known as hydrolases. Examples of such hydrolases are:
1. Carbohydrases which digest carbohydrates:
a) Amylases (e.g. salivary amylase in the mouth and pancreatic amylase) which digest or hydrolyse starch.
b) Cellulases which digest cellulose. Some bacteria are able to produce cellulase. Cellulase is not produced by mammals.
2. Proteases (e.g. pepsin in the stomach) which digest proteins.
3. Lipases (e.g. steapsin in pancreatic juice) which digest fats (lipids)

Note that the name of each enzyme is denoted by the suffix "ase" and it shows the substance on which the enzyme acts e.g. Carbohydrases acts upon Carbohydrates. Previously enzymes were named after their discoveries such as pepsin.
Digestive enzymes are used in some washing powders. They break down and remove stains caused by organic matter e.g. sweat, blood, curry, plant material etc.
Another class of enzymes is the oxidation reduction enzymes which are concerned with the oxidation of food in the process of cellular respiration.