Enzyme inhibition is an important process of regulation within the cell. In this lesson, you will learn what an enzyme is and three ways that it can be inhibited.
What Is an Enzyme?
Enzymes are important workers in a cell. They can put things together, break things apart, and switch things on or off. The molecule (usually a protein) that an enzyme works on is called the substrate.
Like a worker in a factory, an enzyme is fine-tuned to do one specific job. In the cell, this job might be adding a phosphate group, cleaving a protein, or many other functions. Let’s imagine that we have an enzyme that works in a toy factory. Its specific job might be to put the arms on toy soldiers.Enzymes are catalysts that make reactions happen faster. Often, they make the difference between whether a job gets done or whether it doesn’t.
So, if the body wants to turn a reaction on or off, it usually just turns the enzyme on or off. Enzyme inhibitors are a common way that the body turns off enzymes.Inhibitors are usually proteins. They interact with the enzyme in some way to prevent it from doing its job.
There are three major types of enzyme inhibition: competitive inhibition, non-competitive inhibition, and uncompetitive inhibition.
Enzymes have one specific spot on them where they act on a substrate. This part of the enzyme is called the active site. This is where the magic happens.
In our example, the hand of the factory worker would be the active site.A competitive inhibitor binds in the active site. This prevents the enzyme from binding to the substrate.
When the active site is blocked, the reaction cannot occur. It is like the inhibitor and the substrate are competing for the active site. This would be like putting a lunchbox in factory worker’s hands so that he can’t pick up the toy soldier pieces.
Enzymes also have regions that are not the active site, called allosteric sites. In non-competitive inhibition, the inhibitor binds to an allosteric site. This often causes the enzyme to shift into an inactive configuration.
So, even though it binds at another site, it changes the active site and makes the enzyme inactive. This would be similar to putting a blindfold on the factory worker. His hands (the active site) are still free, but it would be much more difficult to perform his job.
There are some inhibitors that are neither competitive nor non-competitive inhibitors.
These uncompetitive inhibitors wait until the enzyme has bound to the substrate. Then, they bind to the enzyme-substrate complex. This prevents the reaction from being completed.
Think of it like wrapping a factory worker’s hands in bubble wrap after he picks up the toy parts.
Enzymes are important, but they must be carefully regulated. Inhibitors are an important way to turn an enzyme off.
They prevent enzymes from actively working on a substrate. Competitive inhibitors bind to the active site. Non-competitive inhibitors bind to the allosteric site. Uncompetitive inhibitors bind to the enzyme-substrate complex. Each of these types of inhibitors keeps the enzyme from doing its job.