Inhibitors of Enzyme

Certain substances present within cells can react with an enzyme and lower the rate of the reaction it catalyses; these substances are called inhibitors. Enzyme inhibitors are broadly divided into two types based on how they interfere with the enzyme: competitive inhibitors, which compete directly with the substrate for the enzyme's active site, and non-competitive inhibitors, which bind elsewhere on the enzyme and change its shape rather than directly blocking the active site. These two mechanisms have distinctly different effects on the enzyme's kinetics: a competitive inhibitor's effect can be overcome by adding enough extra substrate (it raises the apparent Km but leaves Vmax unchanged), while a non-competitive inhibitor's effect cannot be reversed simply by adding more substrate (it lowers Vmax, since some of the enzym …