For a Simple Enzymatic Reaction That Involves Only One Substrate

Short Answer

For a simple enzymatic reaction that involves only one substrate and follows Michaelis-Menten kinetics, the changes in the concentrations of substrate, product, free enzyme, and the enzyme-substrate complex over the course of the reaction are depicted by solid curves in the graph below. Which curve (1 to 4) corresponds to [ES]? Write down the number as your answer.