Name: Protein Denaturation
Uploaded: 2023-06-23T15:38:44
Description: Learn by watching this video about Protein Denaturation at JoVE.com

A protein can only carry out its biological activity in its native conformation under optimal conditions.
Exposure to certain chemicals or heavy metals, or changes in pH or temperature can denature the protein, that is, disrupt its three-dimensional structure and make it biologically inactive.
During denaturation, the covalent and non-covalent interactions holding together the protein&#39;s tertiary and secondary structures break, leading to the uncoiling of helices, the destabilization of beta sheets, or even the complete unfolding of the protein into its primary polypeptide chain.
In some cases, when the optimal conditions are re-established, the denatured protein can refold into its functional form through a process called renaturation.
For instance, when the blood pH falls below 7.35, excess H+ ions bind to hemoglobin, inducing conformational changes in its structure. These structural changes prevent hemoglobin from binding and transporting oxygen.
However, when the normal blood pH is restored, hemoglobin releases the attached H+ ions, reacquires its biologically active form, and resumes oxygen transport.

protein denaturation

The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. Folding of the polypeptide chain takes place under specific conditions that energetically favor the folded conformation. In contrast, protein denaturation occurs spontaneously under unfavorable conditions that disrupt the integrity of the folded conformation. Thus, the chemical and physical environment of a protein, such as significant changes in pH or temperature, influences its stability. In addition, the presence of certain organic compounds, salts, and heavy metals can also lead to protein denaturation.
Temperature-induced Protein Denaturation
When proteins are exposed to a higher temperature, the primary non-covalent interactions, including hydrogen bonds, electrostatic forces, and van der Waals interactions, are disrupted. This is because of the rise in the kinetic energy of molecules due to heat that results in their vigorous vibration. Because of the disorder in non-covalent interactions, the native conformation of protein collapses, leading to denaturation. For example, albumin&#8212; a protein found in eggs, coagulates when an egg is boiled.
Organic Compounds Induced Protein Denaturation
Various organic compounds have the potential to denature proteins. One such chemical is ethyl alcohol, used in sanitizers and disinfectants owing to its denaturing properties. The alcohol disrupts the side chain intramolecular hydrogen bonds within the protein and forms new hydrogen bonds with the protein side chains. This affects the protein&#39;s tertiary structure, resulting in the unfolding of the polypeptide chain and denaturation of the protein.
Heavy Metals Induced Protein Denaturation
Heavy metals such as arsenic, mercury, cadmium, chromium, and lead are toxic because they affect the physiological activities of proteins in the body. These heavy metals either displace the essential metal ion in metalloproteins or form a complex with a functional side chain of the protein. This induces conformational changes in the native structure, hampering the protein&#39;s biological activity. For example, metal ions such as calcium in metalloproteins and zinc in zinc-finger proteins are replaced when a person is exposed to cadmium

Learn by watching this video about Protein Denaturation at JoVE.com

Protein Denaturation

The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. ...