Denaturation is the process of changing the structure of a protein

Denaturation is the process of losing the three-dimensional conformation that protein molecules have. This phenomenon may be temporary or permanent. In any situation, the sequence of amino acid residues in the protein structure is preserved.

Peculiarities

Protein denaturation is associated with a change in temperature. In the case of breaking a significant number of bonds that stabilize the spatial structure of the protein molecule, which is unique, the molecule will completely (or partially) take the form of a random random coil.

Reversible denaturation involves partial changes that do not lead to a complete change in the primary amino acid sequence. In the case of complete destruction, it is impossible to restore the protein structure.

Characteristic

When the biopolymer is heated to 60-80 degrees Celsius or exposed to other reagents that can destroy non-covalent (hydrogen, disulfide) bonds in proteins, denaturation occurs.

This phenomenon is observed at the interface between two phases. In an alkaline or acidic environment, as well as under the influence of organic polar solvents (phenols, alcohols), the protein structure is destroyed.

Mechanism

In some cases, urea or guanidine chloride is used for denaturation, which are capable of forming hydrogen bonds with carbonyl or amino groups of the peptide species, as well as with part of the amino acid radical.

At the same time, they replace the intramolecular hydrogen bonds existing in the protein molecule, which leads to a change in the secondary and tertiary structure of biopolymers. Protein denaturation depends on the presence of disulfide bonds in the molecule.

For example, in the trypsan inhibitor (pancreatic protein) there are disulfide bridges. When they are restored, denaturation is carried out without the use of other denaturing components. Upon subsequent exposure of the protein to oxidizing conditions, the SH-groups of cysteine ​​are oxidized.

As a result of chemical interaction, the initial conformation is restored. The presence of one disulfide bond contributes to a significant increase in the stability of the entire spatial structure.

Denaturation is a process leading to a decrease in the solubility of a protein molecule. As a result, the formation of a precipitate of "coagulated" protein occurs. At a high concentration in a biopolymer solution, complete "clotting" of the mass of the solution is observed.

An example of such a phenomenon would be the transformations observed when boiling a chicken egg. DNA denaturation involves the complete loss of the biological activity of the protein. It is these properties that have contributed to the use of a solution of carbolic acid as an antiseptic.

The high probability of destruction of the structure of protein molecules creates a huge number of difficulties in their isolation, study, and practical use for industrial and medical purposes.

Renaturation

If denaturation is the process of destruction of biopolymers, then renaturation is the reverse phenomenon. Restoration of the native conformation of the protein molecule is possible in the case of slow cooling of the protein destroyed by heating.

This phenomenon confirms the structure of the primary structure of protein molecules. The formation of a native conformation is a spontaneous process that involves the use of a minimum amount of energy.

The spatial structure of the biopolymer uses the coding for the location of the amino acid sequence in the polypeptide. This complicates the process of renaturation of protein molecules.

Conclusion

Protein molecules that have the same or similar conformation can have significant differences in the primary structure. At the same time, different amino acids are similar in chemical and physical characteristics of the side chains. In the process of denaturation, the molecule unfolds, it loses the ability to fulfill its biological purpose.

With ultraviolet or infrared radiation, kinetic energy is transferred to the biopolymer, resulting in the vibration of its atoms. This causes the complete destruction of hydrogen bonds, provokes the folding of the protein molecule.