Denaturation occurs when proteins are manipulated by physical or chemical treatment, their natural structure changes and become “unnatural”.. Treatments such as heating, convey energy to proteins. This energy is enough to break the Hydrogen bonds which hold the protein in its coiled, helical secondary and tertiary configurations. As this process continues, the protein molecule uncoils more and more and the regions that were once internally directed become exposed on the outside of the 3-D structure. The freed, highly hydrophillic peptide bonds attract H2O molecules.
These water molecules are entrapped very closely to the protein strands. The exposed hydrophobic bonds however, do not favour this position for these portions are not stable in aqueous surroundings. For this reason, during the unfolding, hydrophobic bonds on individual protein structures will join with those of other protein structures.
As denaturation continues, these sets comply to hydrophillic regions of the protein and hydrophobic regions dissolve, afford the energy necessary to absorb the structure. Eventually, all the protein molecules initiate into the large, insoluble mass, containing entrapped H2O molecules.
Renaturation is the remodification, breakage and refolding of an unfolded polypeptide chain of a protein to its natural 3-D structure. Smaller proteins are more easily refolded than large ones. Factors such as size, sequence, number of sub-units, amount of inter-amino acid links (disulphide bonds) and how the protein was denatured in the first place, are all essential for its renaturation ability. However, chances are, the denaturing process is almost irreversible!