Enzymes

Living organisms function properly because necessary biochemical reactions happen regularly in our bodies. What controls these reactions primarily? Enzymes are biological catalysts. This article explains how various biological and metabolic reactions are regulated by enzymes, the six types of enzymes, and how lactase enzymes and allosteric enzymes manage various reactions in our body.

A group of hundreds of amino acids together create proteins called enzymes. Enzymes also operate as biological catalysts in various biochemical reactions, increasing the speed of the reactions. Multiple biological functions in the body require the presence of enzymes. 

What are enzymes?

There are almost 1300 enzymes in a human cell. These enzymes combine themselves with other coenzymes and create many chemicals that give humans the ability to think, feel, hear, move, digest food, and see things. 

Enzymes can function on the molecules called substrates and transform them into molecules called products. Various parts of a living body can release enzymes, and they are temperature and pH-sensitive and can get damaged at a temperature above 40 degrees Celsius. 

Enzymes are found in the stomach, small intestines, saliva and pancreas.

Functions of enzymes

One of the critical functions of enzymes is to speed up the chemical reactions happening in the body. As carbohydrates, proteins, and fats contain large molecules in the human body, enzymes break down these molecules into small molecules. 

Another essential role that enzymes play is in signal transmission. A cell transmits a chemical or physical signal controlled by a series of molecular activities to create a cellular response. Enzymes are commonly utilised as molecular scissors to cut DNA fragments to add DNA/RNA segments in biotechnology. Enzymes are routinely added to products like beverages, bread, chocolates, curd, and predigested infant food.

Enzyme structure

Enzymes are typically large, ranging from 62 residues to an average of 2500 residues in fatty acid synthase, as compared to their substrates. Only a small part of the structure, located around the binding sites, is engaged in catalysis. The enzyme’s active site comprises the catalytic and binding sites together. Enzymes are structured in a specific way, whereas substrates are shaped in a way that allows them to fit into the enzyme’s “active site”, as a key fits perfectly in a lock.

In 1961, an enzyme commission was designated by The International Union of Biochemistry to create proper nomenclature and classification of enzymes. There are six different classes of enzymes that cause chemical reactions in the body: oxidoreductases, transferases, hydrolases, ligases, lyases, and isomerases.

EC1- Oxidoreductases

Oxidoreductases are enzymes that catalyse both oxidation and reduction processes. These enzymes function as hydrogen donors while oxidising a substrate. Dehydrogenases or reductases are the enzymes involved. These enzymes are called oxidases when the oxygen atom is the acceptor. Example: reductases and catalases.

EC-2 Transferases

The function of these enzymes as opposed to the function of hydrolases. Ligases build bonds by removing the water component, unlike hydrolases, which break bonds by adding water. Ligases that are involved in ATP synthesis are divided into several subclasses. Example: RUBP Carboxylase.

EC-3 Hydrolases:

These enzymes catalyse the hydrolysis process. Water is used to dissolve single bonds, hence the name ‘hydrolases’. Some hydrolases function as digestive enzymes and break the peptide bonds in proteins. Example: Maltase and amylase.

EC-4 Ligases 

Functional groups are transferred from one molecule to another by these transfer enzymes except hydrogen. Example: Kinase

EC-5 Lyases:  

These enzymes catalyse processes that include the addition of functional groups to break double bonds in molecules or the removal of functional groups to generate double bonds. These enzymes do not need work molecules. Example: carbonic anhydrase.

EC-6 Isomerase: 

These enzymes aid in the formation of isomers by catalysing molecular structure. They’re molecules with chemical formulas that are similar but are arranged differently. Example: triosephosphate isomerase.

Lactase enzyme

The lactase enzyme can be found mainly in mammals. It is also referred to as lactase-phlorizin hydrolase and is found in the brush border of the small intestine of mammals. The presence of lactase enzymes in the human body is seen mainly during infancy. It helps to break down lactose into glucose and galactose, which helps digest whole milk completely. Lactose intolerance happens when there is a scarcity in the secretion of lactase enzymes. In addition to its crucial functions in the human body, lactase enzymes are also used in the food and medical industry.

Allosteric enzyme

The allosteric enzymes feature a binding region for effector molecules separate from the active site. The binding affects the catalytic characteristics of the enzyme by causing conformational changes. An inhibitor or an activator can be the effector molecule. The allosteric site refers to the location where the effector binds. Effectors can attach to allosteric regions on proteins, causing a conformational shift and protein movements. Other molecules generally control the allosteric enzymes.

Allosteric inhibition: In this process, inhibitors bind to a protein, causing all active sites to undergo conformational changes, lowering the enzyme’s activity.

Allosteric activation: The activator attaches to a protein during this process, increasing the function of active sites and increasing enzymatic activity.

Conclusion

Enzymes are proteins made up of thousands of amino acids. Enzymes are why we can see, hear, digest food, and think properly. Further, enzymes help fasten various biochemical reactions happening in a living body. Though enzymes cannot start any chemical reaction, they are adept at decreasing the activation energy needed for a reaction; hence the energy requirements become lesser. Therefore, enzymes perform various functions in the body.