•Enzymes can be inhibited competitively, when the substrate and inhibitor compete for binding to the same active site or noncompetitively, when the
inhibitor binds somewhere else on the
enzyme molecule reducing its efficiency.
•The distinction can be determined by plotting enzyme activity with and without the inhibitor present.
•Competitive Inhibition
•In the presence of a competitive inhibitor, it takes a
higher substrate concentration to achieve
the same velocities that
•were reached in its absence. So while Vmax can still be reached if sufficient substrate is available, one-half
Vmax requires a higher [S] than before
and thus Km is larger.