Why would you expect the rate of an enzyme-catalyzed reaction to increase proportionately to enzyme concentration given an unlimited supply of substrate?

Answer 1

No, since the reaction reaches a max rate depending on the speed of which the Enzyme bonds to the substrate and the speed at which the enzyme catalyzes the reaction to produce enzyme and product (shown below). E + S --> ES (E - enzyme, S - substrate, P - products)

ES --> E + P Thus, if each reaction rate is not equal to each other, the rate of the overall reaction is not only proportional to both the concentration of enzyme and substrate.