When certain proteins are exposed to heat or chemicals, they become denatured, i.e. change state or qualities. Their secondary and tertiary structures are disrupted, while it’s primary structure still remains intact. For instance, when you boil an egg, the protein becomes solid and insoluble, as the weak forces between charged groups and the weaker forces of mutual attraction of nonpolar groups are disrupted at elevated temperatures. Here, the tertiary structure of the protein is lost. In some instances the original structure of the protein can be regenerated; the process is called renaturation.
Both, denaturation and renaturation can be brought about in a variety of ways. Proteins are denatured by treatment with alkaline or acid, oxidizing or reducing agents, and certain organic solvents. Interesting among denaturing agents are those that affect the secondary and tertiary structure without affecting the primary structure. Some of the smaller proteins, however, are extremely stable, even against heat; for example, solutions of ribonuclease can be exposed for short periods of time to temperatures of 90° C (194° F) without undergoing significant denaturation.
Similarly for the process of renaturation, this is difficult in some proteins and simpler in others. For in instance of the egg, the renaturation is not possible. However, for simpler proteins it is quicker and easier. More complex proteins tend to get trapped in false energy minima and are unable to regenerate. In some cases renaturation is possible because the primary structure of the polypeptide, the covalent bonds holding amino acids in their correct sequence is intact. Once the denaturing agent is removed, the protein reverts to its normal state.
This is very interesting. I had been wondering what exactly causes proteins to denature and form prions and this helps shine light on to that topic. If one can remove the denaturing element from a polypeptide, would it be possible to correct a prion and fight prion-based diseases? It will be fascinating to follow this research in the future!
I didn’t know that proteins could be denatured and then renatured. I wonder what complexities in protein structure make them easier to denature and renature than others. I really liked reading your example about the egg, which helped me imagine how heat can change the proteins due to the weak forces between their charged groups and the weaker forces between nonpolar groups.
I was really interested in the denaturation part of our readings this week. Do you think that viruses are ‘defeated’ by the body denaturing the proteins that it is made up of? Besides cooking an egg, I’d be interested in seeing other examples of where denaturation occurs in nature