Enzymes

The chemical reactions of an organism are collectively called metabolism. Metabolic reactions include: 

• catabolism - 'breakdown' reactions
• anabolism - 'build-up' reactions

Enzymes are biological catalysts that speed up metabolic reactions. The enzymes themselves are not changed by the reaction and have to be reused. 

Enzymes are globular proteins.

The theory of enzyme action

In order to catalyse a reaction, the enzyme and substrate must first collide to form an enzyme-substrate complex. Catalysis then takes place on the enzyme surface, according to the equation:

          E + S          >>>          ES          >>>          EP          >>>          E + P

The enzyme is unchanged at the end of the reaction (and the same products are formed whether the reation is catalysed or uncatalysed).

The reaction takes place on a particular…