Denaturation of Proteins and its Causes

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Denaturation of Proteins - Definition, Causes And Process

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What is Denaturation of Protein?

Denaturation of protein is a process that breaks down the strong links or bonds that makes up the protein molecules. Protein molecules in their native or natural form have strong bonds and a highly ordered and stable structure. After denaturation of the protein molecule, the links or bonds weaken, and the molecule takes a more loose or random structure, most of them being insoluble. For instance, when food is cooked, like egg or meat, it becomes firm due to the change in the protein molecules after it receives adequate heat. This process can be reversed to regain the original structure. 

If the denaturation agent is removed, the original structure will be restored. This process is called the renaturation of proteins. 

Causes of Denaturation of Proteins 

Many physical and chemical conditions maintain the stability of the protein molecule. If those conditions are disarranged, the molecular structure will change and cause disruption. 

  • Temperature maintains stability to a great extent. The heat can disrupt hydrogen bonds and non-polar hydrophobic interactions. When heat is applied, it causes the molecules to vibrate, and it increases the kinetic energy, which disrupts the molecular structure.

  • Due to certain changes in the pH level, temperature, and chemical structure, the hydrogen bonds are disrupted, which results in the unfolding of globular proteins and uncoiling of the helix structure. Thus, the denaturation of proteins takes place, and the secondary and the tertiary structures are destroyed. Heavy salts disrupt the protein molecule structure in the same manner as the salts and the bases.

  • Denaturation breaks the covalent bonds and disrupts the amino acid chains. For instance, alcohol of a very high concentration can disrupt the hydrogen bonding in amide groups in the secondary or tertiary protein structure in various amino acid combinations.

Process of Denaturation of Protein

The process of denaturation of protein is discussed below.

  • Denaturation can easily change the secondary, tertiary, and quaternary protein structure. The primary structure remains intact.

  • Heating, acids, and bases can act as an agent to disrupt the protein molecule bonds due to violent physical reaction.

  • The protein molecule structure can also change by heavy metal poisons that bind the functional group to the protein surface.

  • Any physical change or chemical change can do the process. For example, when the egg is boiled, the heat that acts as an agent disrupts the molecular structure and turns the liquid substance into a semi-solid one. Similarly, in beating the egg, the molecular structure is disrupted due to the change in the kinetic energy.  

  • Most of the denaturation process cannot be reversed. However, there is a certain exception in which the process could be reversed, called the renaturation of proteins. For instance, when milk is curdled, it turns into a semi-solid substance called curd due to the molecules' rapid movement and the increase in kinetic energy. However, this entire process cannot be reversed. The curd cannot be converted to milk.  

Extra Facts

  • The duration of denaturation and the temperature required for denaturation varies from sample to sample. 

FAQ (Frequently Asked Questions)

1. What is the process to turn egg whites from clear to white?

Objects like eggs change colour when exposed to heat or high temperature. The protein structure conforms to the most important component of a living creature. The hydrogen bonding dictates the tertiary structure of the protein molecule. When the egg is exposed to a temperature above 41 degrees Celsius, the protein structure is broken down, and it changes form and colour. In this case, it turns from clear to white. The entire liquid form of the egg, which was the state before the process of denaturation, solidifies. There are many different processes to turn the egg white from clear to white.

2. Name the factors that cause denaturation of proteins?

Various reasons cause denaturation of protein. Some of them are an increased temperature that ruptures the protein molecules' structure, changes in pH level, adding of heavy metal salts, acids, bases, protonation of amino acid residues, and exposure to UV light and radiation.

3. How is the process of denaturation of proteins important to human beings?

The process of denaturation is extremely important to living beings. When we ingest food, and it goes to our stomach, the acids present over there, that is, HCL breaks down the protein molecule components so that the body can easily consume the nutrition. Without breaking the secondary and tertiary protein structure, facilitate the working ability of pepsin enzymes to convert it into peptides. Thus, digestion would not have been properly possible without denaturation of proteins.