What is the relationship between reaction rate and enzyme concentration at maximal reaction rates?

At maximal reaction rates, the relationship between reaction rate and enzyme concentration becomes independent of enzyme concentration because all available substrate molecules are saturated with enzyme active sites. In this state, adding more enzyme does not increase the rate of the reaction since there are no additional substrate molecules to bind to the excess enzymes. The reaction rate is determined solely by the catalytic capacity of the enzyme and the availability of the substrate, which is fully utilized at this point.

When enzyme concentration is increased beyond this saturation point, it does not affect the overall reaction rate because the rate-limiting factor is no longer the enzyme itself but rather the concentration of the substrate. Therefore, even if more enzymes are present, they cannot increase the reaction rate further since there aren’t enough substrate molecules to bind to them. This saturation phenomenon reflects the behavior of many enzymes under typical conditions in enzymatic reactions.