A reduction in the rate of a catalyzed reaction by
substances called inhibitors.
Inhibitors may work
by poisoning catalysts for the reaction or by removing
free radicals in a chain reaction. Enzyme inhibition
affects biochemical reactions, in which the catalysts
Competitive inhibition occurs when
the inhibitor molecules resemble the substrate molecules
and bind to the active site of the enzyme, so preventing
normal enzymatic activity.
can be reversed by increasing the concentration of
In noncompetitive inhibition the
inhibitor binds to a part of the enzyme or enzyme-substrate
complex other than the active site, known as an allosteric
site. This deforms the active site so that the enzyme
cannot catalyze the reaction.
cannot be reversed by increasing the concentration
of the substrate.