Principles of Biochemistry (2+1)

8.2.3.6 Enzyme Inhibition

 Most enzymes can be poisoned or inhibited by certain chemical reagents. There are two major types of enzyme inhibitors: irreversible and reversible. 

Irreversible inhibitors: Irreversible inhibitors are those which combine with or destroy a functional group on the enzyme molecule that is necessary for its catalytic activity. 

An example of an irreversible inhibitor is the compound diisoporpyl fluorophosphate (DFP) which inhibits the enzyme acetyl choline esterase, important in the transmission of nerve impulses. Acetylcholinesterase catalyzes the hydrolysis of acetylcholine, a neurotransmitter substance functioning in certain portions of the nervous system.

                                                              Irreversible inhibition ofacetylcholinesterase by Diisopropylfluorophosphate

 

Reversible inhibitors: There are two kinds of reversible inhibitors, competitive and noncompetitive.