Inhibitors

Enzymes work to speed up the rate of reactions. They do so by lowering the activation energy, or the energy needed to reach the transitition state. Activator and inhibitors can increase or decrease the activity of enzymes. Inhibitors decrease the activity of enzymes. They can be classified as reversible or irreversible. Reversible inhibitors are not permanent changes to the enzyme. They include: competitive, uncompetitive, mixed, and noncompetitive (which are a type of mixed). Competitive inhibitor binds to the same place as the substrate, or the active site. Inhibition can be overcome at high substrate concentrations. Vmax is not effected but Km increases. Uncompetitive inhibitors bind to the enzyme-substrate complex and cannot be overcome at high substrate concentration. Vmax and Km decrease. Mixed and noncompetitive inhibitors can bind to the enzyme or the enzyme-substrate. They decrease the Vmax and do not change the Km. Irreversible inhibitors cannot be removed from the enzyme, instead the whole protein would have to be denatured.