Question

Inhibition of acetylcholine by DFP (diisopropyl fluro-phosphate) is

• A. Competitive inhibition
• B. Non-competitive inhibition
• C. Non-competitive irreversible inhibition
• D. Allosteric inhibition

Answer 1

The correct option is C Non-competitive irreversible inhibition

Diisopropyl fluoro- phosphate binds to the active site of enzyme acetylcholinesterase. Acetylcholinesterase enzyme cleaves acetylcholine to form acetate and choline and therefore terminates the action of acetylcholine. Binding of diisopropyl fluoro-phosphate inactivates the enzyme due to which the acetylcholine accumulates and overstimulates autonomic nervous system including heart, blood vessels and glands. This leads to vomiting, salivation, sweating and even death. DFP forms an irreversible covalent bond with acetylcholinesterase and activity can be regained only if new enzyme is synthesized. Thus it renders the enzyme permanently inactive and is a kind of no-competitive irreversible inhibition.

Thus, the correct answer is option C.