Write notes on proteins.

Explanation

Proteins are polypeptide chains of amino acids .
Classification of proteins : proteins can be classified into two type on the basis of their molecular shape.
a) Fibrous proteins : These are fibre like proteins, the polypeptide chains are parallel which are held together by hydrogen and disulphide bonds. these are insoluble in water . Ex. Keratin present in hair, wool silk etc, and myosin in muscles.
b) Globular proteins : In these proteins , the polypeptide chains coil around to give a spherical shape. these are soluble in water . Ex. : Insulin and albumin.
The structure of proteins is explained in four different levels.
a) primary structure b) secondary structure c) tertairy structure d) quaternary structure
Protein Denaturation : The phenomenon of disorganization of native protein structure is known as denaturation . Denaturation results in the loss of secondary , tertiary and quaternary structure of proteins. This involves a change in physical, chemical and biological properties of protein molecules.
Agents of denaturation :
Physica agents - heat , violent shaking , X - rays , UV - radiation
Chemical agents - Acids, alkalies, organic solvents, urea , salt of heavy metals.