Denaturation of Proteins:- Proteins (Globular) are very sensitive to the action of heat mineral acids, alkalies etc. On heating or on treatment with mineral acids, soluble form of proteins such as globular proteins often undergo Co-agulation or precipitation to give fibrous proteins which are insoluble in water. Co-agulation also results in the loss of the biological activity of the protein. This coagulation of proteins is called denaturation of proteins. Chemically denaturation does not change the primary structure but changes the secondary and tertiary structures of proteins.

The co-agulation of white part of egg (albumin) on heating is an example of denaturation of protein. Co agulation of milk protein in presence of lemon juice to form cheese is another example of co-agulation. In certain few cases the reverse denaturation is possible which is known as renaturation.

Biological Functions of Proteins:-

(1). Proteins are the chief structural material of animal tissue e.g. keratin, myosin etc.

(2) They act as the transport agent for many cellular materials such as oxygen. e.g. Hemoglobin.

(3) Many proteins act as enzymes which catalyses biological activities.

(4) Some proteins such as insulin act as regulator of metabolic process.

(5) Proteins as antibodies protect the body from foreign invasion.