What happens to enzyme activity as substrate concentration increases?

As substrate concentration increases, enzyme activity generally exhibits a specific pattern. Initially, as the concentration of substrate rises, the rate of reaction increases since more substrate molecules are available for the enzyme to bind with, leading to more substrate-enzyme complexes being formed. This relationship can often appear to be linear at low substrate concentrations.

However, as substrate concentration continues to increase, the enzyme active sites become saturated with substrate molecules. Once all active sites of the enzyme are occupied, adding more substrate does not increase the rate of reaction; this is where the activity eventually plateaus. This plateau reflects the maximum rate of reaction for that enzyme under the given conditions, known as Vmax.

Thus, while initial increases in substrate concentration can enhance enzyme activity, the saturation effect leads to a limit beyond which further increases in substrate concentration do not yield additional increases in activity. This concept is integral to understanding enzyme kinetics as outlined in the Michaelis-Menten model.