Question

In competative inhibition the inhibitor binds to

Answer 1

Competitive inhibition is a form of enzyme inhibition where binding of an inhibitor prevents binding of the target molecule of the enzyme, also known as the substrate.[1] This is accomplished by blocking the binding site of the substrate - the active site - by some means. The Vmax indicates the maximum velocity of the reaction, while the Km is the amount of substrate needed to reach half of the Vmax. Km also plays a part in indicating the tendency of the substrate to bind the enzyme.[2] Competitive inhibition can be overcome by adding more substrate to the reaction; therefore, increasing the chances of the enzyme and substrate binding. As a result, this alters only the Km, leaving the Vmax the same.[3] This can be demonstrated using enzyme kinetics plots such as the Michaelis-Menten or the Lineweaver-Burk plot. Once the inhibitor is bound to the enzyme, the slope will be affected, as the Km either increases or decreases from the original Km of the reaction.[4][5][6]

Most competitive inhibitors function by binding reversibly to the active site of the enzyme.[1] As a result, many sources state that this is the defining feature of competitive inhibitors.[7] This, however, is a misleading oversimplification, as there are many possible mechanisms by which an enzyme may bind either the inhibitor or the substrate but never both at the same time.[1] For example, allosteric inhibitors may display competitive, non-competitive, or uncompetitive inhibition