Question

What causes competitive inhibition?

Answer 1

Enzymes must sometimes be switched off. When you are cut, for example, a complex system of enzymes and cells in your blood must create a clot to prevent death from blood loss. If these cells and enzymes were always active, your blood would clot without warning and be unable to transport oxygen and nourishment to your body's peripheral tissues.

Complete answer:
Competitive inhibition is generated by a reversible inhibitor (competitive inhibitor) that is chosen by the enzyme's binding site but cannot activate the catalytic site.
Sometimes a molecule has the same structure as a typical substrate and fits into the active site's binding region. As a result, the enzyme will not be available to a regular substrate in this manner.

As a result of the structural similarities with a normal substrate, the binding site selects a competitive inhibitor, but it is unable to activate the catalytic site. Because it is occupying the binding site, it is unavailable to a regular substrate. As a result, there is no product formation. Competitive inhibition is the term for this.

Malonic acid and succinic acid are structurally similar. Succinic acid is a succinic dehydrogenase's particular substrate (enzyme). However, in some situations, malonic acid acts as a competitive inhibitor by binding to the binding site of succinic dehydrogenase but is unable to activate the catalytic site, preventing the formation of products.

The active site is split into two sections:
1. Binding site: This site holds the appropriate substrate and fits it into the enzyme-substrate or ES complex.
2. Catalytic site: This region of the active site converts the substrate into products, hence it's crucial for the enzyme's catalytic activity.

Note:
In competitive inhibition, a molecule that looks like the substrate but can't be acted on by the enzyme competes for the active site with the substrate. Because the inhibitor is present, there are fewer active sites available to act on the substrate. However, because the inhibitor has no effect on the enzyme's overall structure, it can still catalyse the process on substrate molecules that bind to an active site.