Question

What are enzyme inhibitors? Classify them on the basis of their mode of attachments on the active site of enzymes. With the help of diagrams explain how do inhibitors inhibit the enzymatic activity.

Answer 1

Defining Enzyme inhibitors

An enzyme inhibitor is a molecule or a bunch of molecules that binds to an enzyme and somehow inhibits or decreases its activity.

Many drugs are enzyme inhibitors because they can block the active sites of the enzymes or change their shape and cause prevention in the interaction between the enzyme and its substrate or inhibit its catalytic activities.

Classification of enzyme inhibitors
Enzyme inhibitors can be classified into 2 separate categories according to their mode of attachment on the active site of the enzymes.

(i) Competitive inhibitors
(ii) non-competitive inhibitors

Inhibition of enzymatic activity by enzyme inhibitors

(i) Competitive inhibitors

These kind of inhibitors (drugs) usually mimic the chemical structures of a natural substrate that binds to the active site of the enzyme.

They compete with the natural substrate for their attachment on the active sites of the enzyme and thus inhibit the catalytic activity of that enzyme.




(ii) Non-competitive inhibitors

These drugs do not bind to the exact active site of the enzyme, it binds to another site of the enzyme than the active site, which is generally called allosteric site.

This binding of the inhibitors at the allosteric site brings a change in the shape of the active site of the enzyme in such a manner that it will not be possible for the substrate to recognize and bind to the active site of the enzyme.

Therefore, non-competitive inhibitors destroy enzymatic action without any direct interaction with the active site of the enzyme.