inhibition
Last reviewed 01/2018
Enzymes may be inhibited in a variety of manners:
- irreversible; the bond between enzyme and inhibitor is usually permanent. Examples include the inhibition of acetylcholinesterases by organophosphate insecticides such as DFP.
- reversible:
- competitive: both substrate and inhibitor bind to the active site and compete for presence within it. The enzyme has a reduced affinity for the original substrate - Km is reduced.
- non-competitive: the inhibitor binds to an enzymatic site separate from the active site. It does not alter the affinity of enzyme for substrate, but it does decrease the rate at which the enzyme can work - Vmax is reduced.
- uncompetitive inhibition: the inhibitor binds with the enzyme-substrate complex so that it cannot undergo further reaction. It lowers Vmax but increases Km.