Denaturation of Proteins, Process of Denaturation of Proteins, Causes, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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Denaturation of Proteins

  • Denaturation implies the destruction of the tertiary structure of a protein molecule and the formation of random polypeptide chains.
  • Denaturation involves the breaking of many of the weak linkages, or bonds within a protein molecule that are responsible for the highly ordered structure of the protein in its natural (native) state. Denatured proteins have a looser, more random structure; most are insoluble.
  • Denaturation of proteins is one of the phenomenon՚s that results in the disturbance of stability and structure of the protein. The chemistry of proteins has always been important owing to the abundance of these biomolecules in the living system. The fundamental blocks of our body structure and their functioning require protein. This protein is supplied to our body through food products such as pulses, cheese, milk, meat, nuts, etc.
  • Denaturation occurs because the bonding interactions responsible for the secondary structure (hydrogen bonds to amides) and tertiary structure are disrupted. In tertiary structure there are four types of bonding interactions between “side chains” including: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions. which may be disrupted. Therefore, a variety of reagents and conditions can cause denaturation. The most common observation in the denaturation process is the precipitation or coagulation of the protein.
  • Denaturation, in biology, process modifying the molecular structure of a protein. Denaturation involves the breaking of many of the weak linkages, or bonds (e. g. , hydrogen bonds) , within a protein molecule that are responsible for the highly ordered structure of the protein in its natural (native) state. Denatured proteins have a looser, more random structure; most are insoluble. Denaturation can be brought about in various ways e. g. , by heating, by treatment with alkali, acid, urea, or detergents, and by vigorous shaking.
  • The original structure of some proteins can be regenerated upon removal of the denaturing agent and restoration of conditions favoring the native state. Proteins subject to this process, called renaturation, include serum albumin from blood, hemoglobin (the oxygen-carrying pigment of red blood cells) , and the enzyme ribonuclease. The denaturation of many proteins, such as egg white, is irreversible. A common consequence of denaturation is loss of biological activity (e. g. , loss of the catalytic ability of an enzyme) .

What Causes Denaturation of Proteins?

These biomolecules are also required for the proper maintenance of our bodies. We have studied about the different structures of proteins; it has a unique three-dimensional structure.

Denaturation of Proteins

The stability of protein and its structure depends on physical and chemical conditions.

  • Temperature and pH affect their stability to a great extent.
  • Denaturation of the proteins is a condition when the unique three-dimensional structure of a protein is exposed to changes.
  • Due to changes in temperature, pH or other chemical activities, the hydrogen bonds present in the proteins get disturbed. This results in the unfolding of globular proteins and uncoiling of the helix structure.
  • The uncoiling of helix structure affects the chemistry of proteins and they lose their biological activity. This phenomenon of losing their activity and uncoiling of helix structure due to physical or chemical changes is called the denaturation of proteins.
  • During denaturation of proteins, the secondary and tertiary structures get destroyed and only the primary structure is retained.
  • Covalent bonds are broken and interaction between amino-acid chains gets disrupted. This results in the loss of biological activity of the proteins.

Process of Denaturation of Proteins

  • Secondary, tertiary and quaternary protein structure is easily changed by a process called denaturation. These changes can be quite damaging.
  • Heating, exposure to acids or bases and even violent physical action can cause denaturation to occur.
  • The albumin protein in egg white is denatured by heating so that it forms a semisolid mass. Almost the same thing is accomplished by the violent physical action of an egg beater in the preparation of meringue.
  • Heavy metal poisons such as lead and cadmium change the structure of proteins by binding to functional groups on the protein surface.
  • Denaturation of proteins can be done by bringing in physical changes as well as the introduction of chemicals.
  • Most of the denaturation processes are irreversible, but it has been seen (in very few cases) that some of the denaturation processes can be reversed; it is then called as renaturation of protein.
  • Some of the common cases of denaturation of proteins are coagulation of egg white when an egg is subjected to boiling. Here the denaturation occurs due to change in temperature.
  • Curdling of milk is another example of denaturation of proteins where the formation of lactic acid by microbial action results in denaturation.

Questions

What Factors Cause Protein Denaturation?

Answer:

  • Temperature, pH, salinity, polarity of solvent - these are some of the factors that influence the shape of a protein.
  • If anyone or combination of these factors varies from normal conditions the shape (and function) of the protein will change. This change in shape is also called denatured.

What is Cold Denaturation of Proteins?

Answer:

Protein unfolding caused by heating a protein solution from room temperature to higher values is a familiar phenomenon and is simply referred to as “thermal denaturation” whereas unfolding caused by cooling the protein from room temperature to lower values is called “cold denaturation” .

What is Denaturation Process?

Answer:

Denaturation, in biology, process modifying the molecular structure of a protein. Denaturation involves the breaking of many of the weak linkages, or bonds (e. g. , hydrogen bonds) , within a protein molecule that are responsible for the highly ordered structure of the protein in its natural (native) state.

What is Denaturation and Renaturation of Protein?

Answer:

  • When a solution of a protein is boiled, the protein frequently becomes insoluble — i.e.. , it is denatured — and remains insoluble even when the solution is cooled.
  • In some instances, the original structure of the protein can be regenerated; the process is called renaturation.

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