Final answer:
The statement is true; the E-S complex forms at a lower energy level than the transition state, reducing the activation energy barrier in the energy profile for enzymatic reactions.
Step-by-step explanation:
The statement that the E-S complex often shows as a slight depression in the energy profile for the reaction is true. The energy profile of a chemical reaction typically includes an activation energy barrier that must be overcome for the reaction to proceed.
This is true for both exergonic (energy-releasing) and endergonic (energy-absorbing) reactions. The transition state, which is the highest energy state of the reaction, occurs after the activation energy barrier has been surmounted.
However, the enzyme-substrate (E-S) complex forms at a lower energy level than the transition state, which effectively lowers the activation energy required for the reaction to take place, thus showing as a slight depression in the energy profile. This decreased energy requirement facilitates a faster reaction rate.