Final answer:
A noncompetitive inhibitor binds to the allosteric site of an enzyme, altering the active site and preventing substrate binding, which is known as allosteric inhibition.
Step-by-step explanation:
When a noncompetitive inhibitor molecule binds to an enzyme, it attaches to the allosteric site, causing a change in the enzyme's shape and altering the active site. As a result, the substrate can no longer bind effectively, inhibiting the enzyme's activity without directly competing with the substrate for the active site. This process is known as allosteric inhibition and is distinct from competitive inhibition, where the inhibitor resembles the substrate and competes for binding at the active site.
The allosteric site is any site on the enzyme that is not the active site. The attachment of the non-competitive inhibitor to the allosteric site results in a shift in three-dimensional structure that alters the shape of the active site so that the substrate will no longer fit in the active site properly.