Enzymes help with specific functions that are vital to the operation and overall health of the human body. They help speed up chemical reactions and are essential for respiration, digestion, muscle and nerve function, and more.
Each cell in the human body contains thousands of enzymes. Enzymes help facilitate chemical reactions within each cell. Since they are not destroyed during this process, a cell can reuse each enzyme repeatedly.
This article reviews what enzymes are and the roles they play in various parts of the body.
The
Each cell contains thousands of enzymes, which play specific roles throughout the body.
Enzymes help with the chemical reactions that keep a person alive and well. For example, they perform a necessary function for metabolism, the process of breaking down food and drinks into energy.
Enzymes catalyze, or speed up, chemical reactions in cells. More specifically, they
Enzymes provide support for many important processes within the body. Some examples include:
- The digestive system: Enzymes help the body break down larger complex molecules into smaller molecules, such as glucose, so that the body can use them as fuel.
- DNA replication: Each cell in the body contains DNA. Each time a cell divides, the cell needs to copy its DNA. Enzymes play
a few important roles in this process, including unwinding the DNA coils. - Liver enzymes: The liver breaks down toxins in the body. To do this, it uses a range of enzymes that help destroy the toxins.
Other activities enzymes help with include:
- hormone production
- cell regulation
- muscle contraction
- material transportation around a cell
- respiration
- signal transduction
The “lock and key” model was first proposed in 1894. In this model, an enzyme’s active site is a specific shape, and
A newer model, the induced-fit model, helps to account for reactions between substrates and active sites that are not exact fits.
In this model, the active site changes shape as it interacts with the substrate. Once the substrate fully locks in, the catalysis can begin.
Enzymes can only work in certain conditions. For example, many enzymes have optimal temperature ranges in which they work best. At lower temperatures, they may still work, but much more slowly.
If the temperature is too high or if the environment is too acidic or alkaline, the enzyme changes shape; this alters the shape of the active site so that substrates cannot bind to it, resulting in a process called denaturing.
Different enzymes also tolerate different levels of acidity. Many enzymes work well in environments with a
Some enzymes cannot function unless they attach to a specific non-protein molecule, known as cofactors. There are
Ions are inorganic molecules that loosely bond with the enzyme to ensure it can function. By contrast, coenzymes are organic molecules that also loosely bond with and allow an enzyme to do its job.
When a cofactor bonds tightly with an enzyme, it is known as a prosthetic group.
To ensure that the body’s systems function properly, it is sometimes necessary to slow down enzyme function. For instance, if an enzyme makes too much of a product, then the body needs a way to reduce or stop the production.
Several factors can limit enzyme activity levels, including:
- Competitive inhibitors: This inhibitor molecule blocks the active site so that the substrate has to compete with the inhibitor to attach to the enzyme.
- Non-competitive inhibitors: This molecule binds to an enzyme somewhere other than the active site and reduces how effectively it works.
- Uncompetitive inhibitors: This inhibitor binds to the enzyme and substrate. The products leave the active site less easily, which slows the reaction.
- Irreversible inhibitors: This is an irreversible inhibitor, which binds to an enzyme and permanently inactivates it.
Thousands of enzymes in the human body exist to perform thousands of different functions. The following table lays out some examples of enzymes and their functions.
| Enzyme or enzyme group | Function |
|---|---|
| lipases | helps digest fats in the gut |
| amylase | helps change starches into sugars |
| maltase | breaks the sugar maltose into glucose |
| trypsin | breaks proteins down into amino acids in the small intestine |
| lactase | breaks lactose, the sugar in milk, into glucose and galactose |
| acetylcholinesterase | breaks down the neurotransmitter acetylcholine in nerves and muscles |
| helicase | unravels DNA |
| DNA polymerase | synthesizes DNA from deoxyribonucleotides |
Types of enzymes
Experts break enzymes down into several different types based on the functions they perform in the body. The different types include:
- oxidoreductases
- transferases
- hydrolases
- lyases
- ligases
- isomerases
The body needs all of the different types to function properly.
Enzymes play a large part in the day-to-day functioning of the human body. Enzymes work by combining with molecules to start a chemical reaction. They work best at certain pH levels and temperatures.
They play a vital role in the proper functioning of the digestive system, the nervous system, muscles, and more.