Question

Which of the following statements is not true about enzyme inhibitors?

• A. Inhibitors can be competitive or non-competitive.
• B. Generally, a strong covalent bond is formed between an inhibitor and an enzyme.
• C. Inhibit the catalytic activity of the enzyme
• D. Prevent the binding of the substrate.

Answer 1

The correct option is B Generally, a strong covalent bond is formed between an inhibitor and an enzyme.

Analysing the options:

Option (A):
Enzyme inhibitors block the binding site of the enzyme and prevent the binding of substrate or can inhibit the catalytic activity of the enzyme.

Hence, statement (A) is true about enzyme inhibitors.


Option (B):
Inhibitors prevent the binding of the substrates.

Hence, statement (B) is true about enzyme inhibitors.

Option (C):
Inhibitors bind with the enzymes either reversibly or irreversibly. Reversible inhibitor binds non-covalently with enzymes. Generally, weak bonds such as van der Waal’s interaction and hydrogen bonding are formed between the enzymes and an inhibitor.
But if there is a strong covalent bond formed between an inhibitor and an enzyme, the enzymes get blocked, then the body degrades the enzyme-inhibitor complex and synthesizes the new enzyme.
So, inhibitors and enzymes do not form covalent bonds.

Hence, statement (C) is not true about enzyme inhibitors.

Option (D):
Inhibitors can be classified as competitive or non-competitive.

• Drugs compete with the natural substrate for their attachment on the active sites of enzymes. Such drugs are called competitive inhibitors.
• Some drugs do not bind to the enzyme’s active site. These bind to a different site (allosteric site) of the enzyme which changes the shape of the active site in such a way that the substrate cannot recognize it.

Such drugs are called non-competitive inhibitors.

Hence, statement (D) is true about the binding site of enzymes.

So, option (C) is the correct answer.