Enzymes

Enzyme Definition and Functions

An enzyme is defined as a biological polymer that catalyzes biochemical reactions. Most of the enzymes are proteins that have catalytic capability.

They are responsible for carrying out functions of life such as chemical processes in cells and other metabolic functions. Enzymes are regulated strictly to ensure that reactions occur at the appropriate times and locations within a cell.

The initial step of metabolism functions involves the reaction of a molecule with an enzyme, resulting in a substrate. Further, this substrate is converted by the enzyme into a product, which is another distinct molecule.

Types of Enzymes

As discussed above, enzymes are catalysts for any metabolic or chemical functions in the body. Lets now know what are the 5 enzymes in our body that carry several roles:

1. Transferases – This enzyme is responsible for transferring functional groups such as phosphate or methyl group, from one molecule to another. This is essential for carrying out different body functions like metabolism and cell signaling. Example – Hexokinase.
2. Oxidoreductases – The enzyme is involved in the oxidation-reduction process, where the transfer of electrons takes place between molecules. The enzyme is important for cellular respiration and energy production. Example – Cytochrome oxidase.
3. Hydrolases – This enzyme is responsible for hydrolyzing the bonds in various chemical reactions. The enzyme helps in breaking complex molecular bonds into simpler ones. Example- catalyzing the hydrolytic bonds of peptide bonds in proteins or ester bonds in lipids.
4. Ligases – The enzyme helps in the bonding of two molecules, which requires energy in the form of ATP. The role of ligase is also seen in processes like DNA repair and replication.
5. Isomerases – These enzymes help in the re-arrangement of atoms in the molecules to form isomers. This is important for cellular functions as it helps in forming the structural integrity of the molecules.

Also Check: Applications of Enzymes

How Do Enzymes Work?

Enzymes help in several functions that are essential for our body. They help speed up the metabolic functions in the body. This becomes important for respiration, digestion of food, muscle and nerve function, and more.

Conditions for the enzyme to work

Enzymes need favorable conditions to start working. It involves the following factors-

• In the human body, the enzyme is pro-active at a temperature around 98.6 degrees Fahrenheit (F) (37°C). This is also the normal body temperature of humans.
• If the temperature is low, the enzyme rate also becomes slow.
• If the temperature is too high, it leads to denaturation.
• At high temperatures, if the environment becomes too acidic or alkaline, it changes shape, altering the shape of the active site.
• Enzymes tolerate differently with different temperatures. Like – the enzymes present in the intestine work best at 8 pH, whereas enzymes in the stomach are highly acidic and work best at 1.5 pH.

What is the Structure of Enzyme?

Structure of an enzyme is very important as it decides the functions of the body. It does so by binding to substrates and catalyzes reactions. Here is the outline of the structure of enzyme.

• The “Lock and key” structure of the enzyme was first proposed in 1894.
• According to this model, the active site of an enzyme is shaped like a lock, and only the substrate fits into it.
• The induced-fit model is a newer approach that helps to account for non-exact matches between substrates and active sites.
• The active site in this model changes form as it interacts with the substrate.
• Catalysis initiates once the substrate has fully locked in and is in the proper position.

Characteristics of Enzymes

The enzymes exhibit different characteristics which are mentioned below.

Specificity

• Enzymes are specific and can catalyze only one chemical reaction. Example – In the case of the enzyme urease, it can only hydrolyze urea to NH3 and CO2.

Efficiency

• Enzymes accelerate the biological process in the body at a faster rate.
• In the presence of an enzyme, the biological, chemical, or metabolic process fastens up 100 times more.
• The reactions take place at the body temperature and physiological pH range.

Enzyme activators

• They are also termed coenzymes and are responsible for boosting the enzyme activities in a reaction.
• Coenzymes are derived from vitamins and other organic molecules.
• They help in the transfer of electrons, atoms, or functional groups.
• Example – CoA (Coenzyme A), derived from Vitamin B5, forms acetyl-CoA, a key molecule that enters the Krebs cycle for energy production.

Reusability

• Enzymes are not wholly consumed during the reaction they catalyze.
• This way, the enzyme can be re-used to catalyze a large number of reactions over time.

Reaction rate dependence

• The rate of enzyme-catalyzed reactions is determined by the concentration of substrate molecules present.
• The reaction rate increases as the concentration of substrate increases until the enzyme is saturated.
• At saturation, the reaction attains its maximum rate (Vmax).

FAQs on Enzymes

What are enzymes and their functions?

Enzymes are biological polymers that catalyze biochemical processes. They are in charge of performing life-sustaining operations such as chemical processes in cells and other metabolic functions.

Mention enzyme examples in food

Enzymes such as amylase breaks down starches into sugars, protease breaks down proteins into peptides and amino acids, and lipase breaks down fats into fatty acids and glycerol. Amylase is found in bread, and multigrain foods. Protein can be found in meats, chapati, and legumes. Lipase can be found in dairy products like cheese.

What factors can affect enzyme activity?

Factors such as pH, temperature, substrate concentration, and the presence of inhibitors or activators can affect the enzyme activity. High temperature and pH levels can alter the enzymes and make them inactive. Likewise, inhibitors can interfere with substrate binding by blocking the active site.

How do enzymes work in the human body?

Enzymes in the human body work by fastening the process of chemical reactions. The process starts by lowering the activation energy required. This allows processes like digestion and metabolism to occur efficiently. They function by binding to certain substrates at their active sites. Hence, generating enzyme-substrate complexes that help in the conversion of substrates to products.

Why are enzymes important?

Enzymes are important as they increase the rate of biochemical reaction, which is helpful in digestion, cellular processes, metabolism, and others.