What effect does increasing substrate concentration have on a saturated enzyme-catalyzed reaction rate?

In enzyme kinetics, the relationship between substrate concentration and reaction rate is often depicted using the Michaelis-Menten model. When an enzyme is saturated, the active sites of the enzyme molecules are fully occupied by substrate. At this point, adding more substrate does not significantly alter the rate of reaction.

When the reaction is saturated, every active site on the enzyme is engaged, and the enzyme is operating at its maximum capacity (Vmax). Even if additional substrate is added, there are no free active sites available to bind the new substrate molecules, meaning the reaction rate plateaus. This situation illustrates the concept of saturation kinetics, where the enzyme's efficiency is maximized and is no longer dependent on substrate concentration.

Thus, increasing substrate concentration beyond this saturation point results in no further increase in the reaction rate, confirming that the correct answer is that it causes no further increase in the reaction rate. This understanding is crucial for interpreting how enzymes function in biochemical reactions and is a fundamental concept in studying enzyme kinetics.