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Enzymes Definition

Enzymes refer to the protein that fastens all the chemical reactions in our bodies. They play a significant role in the human body as they help digestion, liver function, and other processes. Excess or deficiency in the number of these enzymes may cause some serious health issues. These enzymes also help in detecting other diseases and illnesses. Every living being has enzymes in them. Our body has a natural process of creating enzymes, which are also produced in food and products. Enzymes build and break some elements in the body. The first stage of the metabolic process is highly dependent upon enzymes, which then react with a molecule and thus are known as substrate.

Enzymes are a linear structure of amino acids which thus turns into a three-dimensional structure. This sequence of amino acids decides the type of catalytic activity to be performed by the enzyme.

Enzymes Definition

Functions of Enzymes

  • Enzymes help in breaking down the consumed food into energy or in the process of digestion. Enzymes are present in saliva, intestines, stomach, and pancreas and then turn the food into proteins, carbohydrates, and fats, which are then used for cell repair and growth. Not only this, but they also help in the process of breathing, nerve function, releasing toxins, and building muscle.
  • Enzymes help in transmitting signals throughout an organism's body, and this process is known as signal transduction. Kinase is the commonly used enzyme that phosphorylation of proteins.
  • Enzymes break down the larger molecules or substances into smaller ones, easily absorbed by the body.
  • These enzymes produce energy with the help of the ATP synthase enzyme.
  • They also aid in the movement of ions across the plasma.
  • Enzymes enact many reactions like oxidation, hydrolysis, reduction, etc.
  • Enzymes organize the structure of the cell to keep regulating the activities of the cell.

Types of Enzymes

There are different enzymes present in our body that play their specific role. e.g., an enzyme named carbohydrase turns carbohydrates into sugar, lipase breaks fat into fatty acids, and protease turns protein into amino acids.

Enzymes are categorized into six categories:

  • Oxidoreductases:- It catalyzed the biochemical oxidation and reduction reaction.
  • Transferases:- These enzymes aid in delivering the functional group from one to another compound.
  • Hydrolases:- These enzymes catalyzes the biochemical hydrolysis reaction by adding water and hydrolyzing it.
  • Lyases:- These enzymes either add or reduce the water, carbon dioxide, and ammonia in double bonds or create new ones.
  • Isomerases:- These enzymes change the molecule's shape by catalyzing the structural shifts in the molecule.
  • Ligases:-Ligases charge the catalysis of a ligation process.

Structure and working of an Enzyme

Enzymes are seen as a lock and key model, which was proposed in 1894. The enzyme has an active site in its structure in which only a substrate will fit as a key in its lock.

A new model has been introduced, known as the induced-fit model. In this model, the active site changes its shape per the requirements to fit the substrate properly. It starts its catalysis process once the substrate properly fits the active site.

Each enzyme consists of an "active site". The active site is a pocket created by amino acids that perform catalysis and binds the substrate. Glutamate, Aspartate, and Histidine are some amino acid residues that act as acceptors and donors of protons.


Some cofactors are present, in the absence of which some enzymes can't work properly. These factors are non-protein molecules of two types: ions and coenzymes. Both of them attach loosely to the enzyme to support it in its functioning. The only difference between ions and molecules is that ions are inorganic molecules, whereas coenzymes are organic. When these cofactors create a tight bond with the enzyme, the term becomes known as the prosthetic group. In short, cofactors are non-protein molecules that attach to enzymes and aid them in their proper functioning.

Catalysis working mechanism

There are four major working of catalysis: covalent catalysis, bond strain and catalysis, acids and bases catalysis, and orientation and proximity catalysis.

  • Covalent Catalysis:- Under this mechanism, a covalent intermediary develops between the enzyme and substrate.
  • Catalysis by Bond Strain:- Strained substrate bonds are created in this catalysis mechanism, which is easy to transit.
  • Catalysis by acids and bases:- This mechanism gives input in completing the catalysis process.
  • Catalysis by Orientation and Proximity:- Under this mechanism, the interacted enzyme and substrate persuade reactive groups near one another.

Factors affecting the activities of Enzymes

Proper conditions must be present to prevent the enzyme from changing its shape to fit the substrate and perform its functions properly. Enzymes generally work properly under moderate temperatures. Under high temperatures, there is a drastic drop in the activity of enzymes.

  • Temperature and pH: Enzymes need a moderate temperature and pH for their proper working. The temperature at which a compound does maximum activity is referred to as the optimum temperature and the pH at which it performs the maximum work is referred to as the optimum pH. Usually, an optimum pH lies in the range of 5 and 7. Enzymes are known as protein compounds.
  • Type of Substrate: The kind of substrate is another factor affecting the enzyme's activity. A chemical that binds the active site retains the potential of the enzyme's activity, and this kind of substrate is known as an inhibitor.
  • Salt Concentration: Changes in salinity are another factor that affects the enzyme's activity. It can disrupt bonds and their 3D shape. It can disrupt attraction between the charged amino acids.

Some examples of Enzymes

  • Depending on distinct factors, enzymes are used for fermentation in alcoholic beverages.
  • Enzymes are very helpful in the production of loaves of bread. They are used for fermentation, due to which the puffiness of bread occurs.
  • They are also very useful for the production of drugs.

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