Some enzyme inhibitors bind weakly and reversibly.
An inhibitor may compete for the active site so a substrate is
less likely to bind when the inhibitor's concentration
is high. They are competitive.
An inhibitor may bind to a part of the enzyme away
from the active site. It affects activity of the active
site but there is no competition with the substrate. It
is non-competitive.
Some enzyme inhibitors bind to the enzyme
irreversibly. This is why some heavy metals are very
poisonous.
Reversible inhibition regulates some metabolic
pathways. A product inhibits an enzyme in the pathway
when it starts to build up.
