enzymes

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life. Like all catalysts, enzymes work by lowering the activation energy for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Synthetic molecules called artificial enzymes also display enzyme-like catalysis.

There is a huge amount of enzymes and they can be classified into six groups: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases.