Question

Explain the primary, secondary, tertiary and quaternary structure of the proteins.

Answer 1

1.Primary structure of proteins: proteins have one or more polypeptide chains. each polypeptide in a protein has amino acids linked with each other in a specific sequence and the sequence said to be Primary structure.

that means the sequence of amino acids create a different protein. thus it represent its constitution.

2. the secondary structure of protein refers along polypeptide chain.

they are found to exist two different types of structures such as

a)-helix:

it is one of the mostcommon ways in which a polypeptide chain forms all possible hydrogen bonds by twisting into aright hand screw(helix)

b) - pleated sheet structure:

in this structure all peptide chains are stretched out to nearly maximum extension and then laid side by side which are held together by inter molecular hydrogen bonds between two chains. the structure resembles pleated folds and therefore is known as - pleated sheet.

c) tertiary structure of proteins:

it representsoverall folding of the polypeptide chains i.e. further folding of the secondary structure. it give

rise to two major molecular shapes such as

a)fibrous and b) globular

the main forces which stabilise the secondary and tertiary structures of proteins are hydrogen bonds, disulphide linkages,vanderwall and electrostatic forces of attraction

d) Quartenary structure of proteins:

some of the proteins are composed of two or more polypeptide chains refered to as sub units. the spatial arrangements of these subunits with respect to each other is known as quartenary structure.