Figure 3.

Schematic illustration of the roles of the interaction potential in three regions around the active site of an enzyme. The binding region is where the substrate can get bound (e.g., via a covalent bond) to the enzyme. The near region is right outside the binding region. This is where a substrate tends to stay for a relatively long time after diffusing out of the binding region. The far region is the rest of space. The potential in the near region is critical for rate control. If it does not differ significantly from the potential in the binding region, then the average Boltzmann factor in the binding region can predict the rate enhancement via Eq. 1 and at the same time the potential in the far region is unimportant. Otherwise Eq. 1 will not be valid.