Enzymes

 Definition :

Enzymes are water soluble, colloidal organic macromolecules which are wholly or partially proteinaceous in nature; biological in origin;  produced in microamounts and capable of catalyzing specific biochemical reactions under specific conditions of temperature and pH. 

Chemical nature 

All enzymes are proteins but all proteins are not enzymes . Enzymes are wholly or partially proteinaceous in nature. This was first shown by J. B. Sumner.  and further supported by Northrop. 

1. Both enzymes and proteins, when boiled with strong acid or base, undergo coagulation and lose their biological function. 
2. Enzymes, like the protein, are macromolecules having high molecular weight ranging from 12,000 to 1million Daltons.
3. Enzymes, on hydrolysis, yield a mixture of amino acids. 
4. Enzymes and proteins both do not pass through dialyzing membrane. 
5. Both are colloidal in nature   

Importance of Enzymes

A biological system needs the enzymes for two reactions :

1. Metabolic actions occur at controlled temperature as these reactions would normally occur outside the body cells at very high temperature which may burn the cells. 
2.  These act as biocatalysts to speeden the rate of biological function ,or slow down to meet the energy needs of body. Some enzyme catalysed reactions are about 10million times faster than the non - catalysed reactions.

Absence of enzyme May be fatal e. g.  Absence of enzyme hexose aminidase in a child leads to a fatal Tay Sach's disease.