What is the difference between competitive and non-competitive Inhibition?

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The primary difference between the competitive and non-competitive Inhibition is that the binding of the inhibitor to the active enzyme’s site refers to the competitive Inhibition whereas, in the case of non-competitive Inhibition, it refers to the inhibitor binding to enzyme at a point other than the active site.

We will get through all the differences between competitive and non-competitive Inhibition but first, let us go through its definitions.

What is competitive Inhibition?

Competitive Inhibition refers to a type of reversible Inhibition where the inhibitor molecules bind to the enzyme’s active site. For this binding to happen, the inhibitor molecules have to compete with substrate molecules, and therefore, the inhibitor molecules’ conformation is similar to the substrate molecule.

Also, they are chemically similar to substrate molecules, and therefore, they can bind to the enzyme active site chemically. However, the inhibitor molecule binding blocks the enzyme’s active site resulting in substrate accumulation while increasing the substrate concentration.

What is non-competitive Inhibition?

Non-Competitive Inhibition refers to a type of reversible Inhibition where the inhibitor molecules bind to the enzyme-substrate complex at an allosteric site other than the active one. In this type, the inhibitor molecule binding to the allosteric site results in a conformation modification in the enzyme’s active site.

It changes the active site’s specificity to a corresponding substrate while making the active site unavailable for the binding process. As the non-competitive inhibitors do not directly compete with the substrate, they do not even modify the substrate concentration.

Key Differences between competitive and non-competitive Inhibition

Competitive Inhibition	Non-Competitive Inhibition
It is similar in conformation to the substrate.	It has a diverse conformation to the substrate.
It competes with the substrate to bind to the enzyme’s active site.	It binds to the enzyme-substrate complex.
The enzyme’s blockage of action of its substrate by the substrate replacement with an identical but for an inactive compound which can combine with enzyme’s active site but is not split or acted upon by the enzyme.	Here the inhibiting enzyme does not compete with the natural substrate on an active site on the enzyme but inhibits the reaction by combining with enzyme-substrate complex post complex formation.
Here the molecules compete with the substrate to bind to the enzyme active site.	Here the molecules bind to enzymes at a site other than the enzyme’s active site.
It increases the substrate concentration	It does not modify the substrate concentration.
It blocks the enzyme’s active site.	It is responsible for the size or shape distortion of enzymes and destabilizing the enzyme-substrate complex.
It dissociates from the enzymes within a shorter time.	It remains bind to the enzyme for a considerable time until the substrate becomes available.

Bottom Line!

Competitive Inhibition is a reversible enzyme inhibition where the inhibitor competes with the substrate to bind the enzyme’s active site and increases the substrate’s concentration.

On the contrary, the non-competitive Inhibition is also a reversible enzyme inhibition where the molecules bind to the enzyme-substrate complex at some other site instead of the active site and change the active site’s conformation while dissociating the enzyme-substrate complex before the formation of the product.

Therefore, the primary difference between both is the type of binding of the inhibitor molecule to the enzyme.