The active site is the region of an enzyme whose shape and chemical groups are complementary to the substrate, and where binding and catalysis take place. The close fit between active site and substrate accounts for the enzyme's specificity. By binding the substrate, the active site lowers the activation energy of the reaction.

活性部位是酶上形状和化学基团与底物互补、并发生结合和催化的区域。活性部位与底物之间的紧密契合解释了酶的特异性。通过结合底物,活性部位降低了反应的活化能。