ABSTRACT
Active site The active site is the region of the enzyme that binds the substrate, to form an enzyme-substrate complex, and transforms it into product. The active site is a threedimensional entity, often a cleft or crevice on the surface of the protein, in which the substrate is bound by multiple weak interactions. Two models have been proposed to explain how an enzyme binds its substrate: the lock-and-key model and the induced-fit model.
