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Denaturation is a combination of the words “denature” with the suffix “ion.” The term “denature” comes from the French “dénaturer,” which is derived from the Latin “dis”-, which means “apart,” and “nātūra,” which means “nature.”
What is Denaturation?
Denaturation is the process by which a molecule structure deviates from its initial state when exposed to a denaturing substance in biochemistry. Proteins and nucleic acids are examples of biomolecules that denature in biology (e.g. DNA).
For example, a denatured protein is one whose three-dimensional (3D) structure has been disturbed as a result of exposure to specific chemical or physical causes (called denaturants). Heat, radiation, acid, solvents, and other denaturants are examples of denaturants.
When a protein is exposed to a denaturant, its structure is changed, and its biological activity and function are lost. Denaturement of nucleic acid, such as DNA, is possible in addition to protein denaturement.
When DNA is exposed to heat, for example, its 3D structure may alter. Due to the dissociation of the two strands caused by heating, it can change from a double-stranded molecule to a single-stranded molecule.
Denaturation is described in the food business as the purposeful adulteration of food or drink (e.g., alcohol) to render it unsuitable for human consumption, such as by adding a toxic chemical.
Denaturation may be classified into two categories based on the cause: biologically induced and non-biologically caused.
i. Biologically-induced Denaturation
When the hydrogen bonds between the nitrogenous base pairs are disrupted, denaturation of DNA causes the double-strand to unravel. In biological systems, this is a type of denaturation that happens. DNA replication, transcription, and DNA repair are all physiologically significant DNA activities.
The double-stranded DNA unwinds in these processes, and the two strands become partly split, creating the so-called “bubble.” In transcription, for example, a portion of the DNA unwinds to produce a transcription bubble, from which an RNA polymerase docking site emerges.
ii. Non-Biologically-induced Denaturation
Non-biologically-induced denaturation refers to a process that is not biological in origin but is triggered by a chemical or physical agent. Heavy metals and metalloids, for example, can damage biomolecular structures.
Protein denaturation is caused by them in a variety of ways. When these compounds react through their functional side groups or oxidise the amino acid side chains, for example, proteins are denatured.
They may also cause metal ions in metalloproteins to dislocate. Chemicals (acids or bases) can cause denaturation via changing the pH, in addition to directly altering protein structure.
Acids that cause the physiological pH to fall below 5 can produce acid-induced protein unfolding, while bases that cause the pH to increase to 10 or higher can cause base-induced protein unfolding.
Extreme temperature, radiation, salt, pressure, and electronegative substances in the atmosphere (e.g. nitrogen and oxygen) are all examples of physical stress that can induce protein and nucleic acid denaturation.
Effects of Denaturation in Biomolecules
A biomolecule, such as a nucleic acid or a protein, deviates from its original structural state due to denaturation. This indicates that the monomeric units that make up the molecule’s sequence may not change. The original 3D structure of the biomolecule is broken during denaturation.
When enzymes (catalytic proteins) are exposed to denaturing chemicals, they unfurl and lose their active site (e.g. strong acids or bases, heat, solvents, and salts). Peptide bonds between amino acids in a sequence are less vulnerable to denaturation than hydrogen bonds.
The structural folding of denatured enzymes is therefore disrupted by denaturation. When the structural folding of proteins is disrupted, their 3D form is harmed, and their role as biological catalysts is lost. How?
Protein maturation is a post-translational process in protein synthesis. A linear polymer of amino acids will appear as the freshly produced protein. Then it folds into a three-dimensional molecule.
Hydrogen bonds are formed inside the framework to produce the 3D shape. The final result is a mature protein with a unique structure and a “active site” that can bind to certain substrates. When a protein is exposed to a denaturant, however, the hydrogen bonds that help create the protein’s 3D structure are destroyed.
The protein structure is disrupted as a result of this. The “active site” has likewise vanished. As a result, substrates that could previously bind to the enzyme’s active site will no longer be able to do so after denaturation. As a result, the biochemical reaction that is triggered by the enzyme interacting to the substrate will be interrupted.
This describes how organisms can be killed by severe circumstances such as extended exposure to radiation, heat, or powerful chemicals. These denaturing chemicals can disrupt the hydrogen bonds that enable these biomolecules to develop their 3D shapes. Hydrogen bonds appear to be a weak form of chemical connection that is quickly broken by heat, radiation, and other stresses.
The presence of denatured proteins or nucleic acids indicates that cell function may be disrupted. If the cell does not repair the disruption, it is in risk of dying prematurely. If the denaturing agent is removed, the proteins can return to their original active form.
There are, however, times when the process is irreversible. Proteins must be folded correctly before they can function. Nucleic acids, on the other hand, must retain structural stability to reduce the chance of mutation.
Otherwise, the body is at danger of contracting a sickness. Blindness, Alzheimer’s disease, and a variety of other neurological disorders are caused by protein denaturation and aggregation. Alcohol denaturation in the food business is not explained by denaturation, which requires a change in chemical structure.
It’s a unique perspective. In this case, denaturation does not imply a structural change, but rather the addition of a toxic chemical to a meal or drink. Denatured alcohol, for example, does not have a changed chemical structure; it just includes additives that make it unpleasant to humans.
Denaturation is an important stage in many DNA activities at the cellular level (as described above). It permits replication or transcription to occur by partly “opening” the DNA. Otherwise, DNA strands may not be replicated in preparation for mitosis or for the production of an mRNA transcript for protein translation.
Denaturation is utilised by the body to eliminate infections at the biological system level. It accomplishes so via regulating pH and secreting biochemicals. Food digestion necessitates denaturation as well. The activity of released digestive enzymes denatures proteins in meals.
The same concept is used in medicine when utilising a denaturation mechanism to destroy bacteria, viruses, and other disease-causing cells. Denaturation is a preferred step in a polymerase chain reaction, which is a technique for rapidly producing multiple in vitro copies of DNA.