When we talk about denaturing a protein we just mean that the natural structure of said protein may be altered, their biological activity may be changed or destroyed. This however does NOT disrupt the primary structure.
In denaturation some proteins would be able to return to their native structure, this depends on proper conditions, but under extreme conditions such as strong heating it would usually cause irreversible changes.
Different denaturing processes include :
Heat – because of increased translational and vibrational energy hydrogen bonds can be broken. ( coagulation of egg white albumin and frying)
Ultraviolet Radiation – this is similar to heat ( sunburn)
Strong acids or bases – salt formation , disruption of hydrogen bonds.
Urea – Competition for hydrogen bonds. ( precipitation of soluble proteins)
Some organic solvents – change in dielectric constant and hydration of ionic groups.
Agitation – Shearing of hydrogen bonds. ( beating an egg white albumin into a meringue)
- Denaturing of proteins usually occurs by heat , and this affects the interactions within a protein molecule
- As temperature increases in a slow manner, the protein’s conformation generally remains intact until an abrupt loss of structure and this occurs over a narrow temperature range.
- Because of the abruptness this change suggest that unfolding is a cooperative process which means loss of structure in one part of the protein destabilizes the other part.
- Solubility drastically decreases as in heating egg white, this is where the albumins unfold and coagulate.
- Because most enzymes are made up of proteins, it is only natural that when they denature they lose their catalytic power.
Proteins can also be denatured by chemicals two of which are
- Chaotropes are ions that enhances the solubilty of non polar compounds in water by disordering the water molecules. Some examples if chaotropes are SCN- , thiocynate and CIO4- , perchlorate , the guaniduim ion and the nonionic compound urea.
- The water molecules disrupt the hydrophobic interactions that normally stabalize the native conformation
- The hydrophobic tails, of detergents such as sodium docecyl sulphate (SDS) also denature proteins by penetrating the protein interior and disrupting hydrophobic interactions.