Final answer:
A noncompetitive inhibitor binds to an enzyme away from the active site and can attach to either the free enzyme or the enzyme-substrate complex, leading to a decrease in the Vmax without affecting the Km. Option 3 is correct..
Step-by-step explanation:
The subject of the question is enzyme inhibition in the field of Biology, specifically relating to a noncompetitive inhibitor. A noncompetitive inhibitor can function by binding to either the free enzyme or the enzyme-substrate complex. Its binding site is distinct from the active site, which means it does not prevent the substrate from binding to the enzyme. Instead, this type of inhibitor changes the conformation of the enzyme, leading to a decrease in the enzyme's activity. As a consequence, a noncompetitive inhibitor will indeed decrease the maximum rate of the reaction (Vmax), without affecting the affinity of the enzyme for its substrate (Km).
A noncompetitive inhibitor can bind to either the free enzyme or the enzyme-substrate complex because its binding site on the enzyme is distinct from the active site. Binding of this kind of inhibitor alters the three-dimensional conformation of the enzyme, changing the configuration of the active site with one of two results.