Classes of Protein and Their Folding

The protein is functionally active in its three-dimensional native state. Almost all cells' machinery is based on the involvement of number of proteins. Structural code of proteins is hidden into the primary structure containing sequence of amino-acids. It has always been a topic of research to investigate the mechanism of determining proteins' three-dimensional details from its primary structure. Studies on protein folding have shed various important facts; viz. the internal core of globular protein is formed by hydrophobic amino acid residues which are held together by van der Waals forces while surface is dominated by charged and polar side chains. Native state of the protein is the most active and stable state with a specific conformation determined by polypeptide backbone and intermolecular interactions. Native state of the protein has lowest free energy due to hydrophobic and electrostatic interactions as well as hydrogen bond energy. Further lowest conformational entropy due to constrains imposed by ψ and φ bonds of main and side chains.