Explain different levels of protein organization.

Explanation

Structure of Protein :
Protein is synthesised on the ribosome as a linear sequence of amino acids which are held together by peptide bonds. After synthesis , the protein attains conformational change into a specific 3D form for proper functioning . According to the mode of folding , four levels of protein organisation have been recognised namely primary , secondary, tertiary and quaternary.
1. The primary structure is linear arrangement of amino acids in a polypeptide chain.
2. Secondary structure arises when various functional groups are exposed on outer surface of the molecular interaction by forming hydrogen bonds. This cases the aminoacid chain to twist into coiled configuration called `alpha`-helix or to fold into a flat `beta`- pleated sheets.
3. Tertiary protein structure arises when the secondary level proteins fold into globular structure called domains.
4. Quaternary protein structure may be assumed by some complex proteins in which more than one polypeptide forms a large multiunit protein . The individual polypeptide chains of the protein are called subunits and the active protein itself is called a multimer.