Substances called catalysts can speed up many chemical reactions.

The first 200 words of this essay...

Substances called catalysts can speed up many chemical reactions. Enzymes are biological catalysts and were discovered by the German chemist Edward Buchner.

Enzymes can be divided into two groups intracellular and extra cellular. Intracellular occur inside the cell where they control metabolism. The latter are produced by cells but achieve their effects outside the cell they include the digestive enzymes that breakdown food.

Enzymes are always proteins and their characteristics therefore reflect the properties of proteins. Their main properties are as follows

1. They generally work very rapidly. The fastest known enzyme is Catalyse. Found in the tissues it speeds up the decomposition of hydrogen peroxide into water and oxygen.

2. Enzymes are not destroyed by the reactions they catalyse and so can be used again. This property can be explained by examining how an enzyme works. When an enzyme controlled reaction takes place the enzyme substrate complex. With their various bonds held in relation to each other by the enzyme the substrate molecules react together to form an enzyme product complex. This splits into the enzyme unchanged by the enzyme and product. The enzyme unchanged by the reaction can be used again.