Structure of Proteins

There are four basic structural levels of Proteins:

1. Primary Structure: A polypeptide chain having a linear sequence of Amino Acid is called Primary Structure. Disulphide (S--S) bond is other important characteristics of the Primary Protein.
2. Secondary Structure: When a polypeptide chain of Amino Acids become spirally coiled this structure is called Secondary Structure of protein. It results in the formation of a rigid and tubular structure called Helix.
3. Tertiary Structure: The term Tertiary Structure refers to the arrangement of secondary structure into the three dimensional (Fold or super fold) structure.
4. Quaternary Structure: It is the association of 2 or more sub-units (polypeptide chain) into large sized molecules is called Quaternary Structure.