Enzyme-catalyzed reactions are limited in their rate of reaction despite increasing the concentration of reactants due to enzyme saturation.
Enzymes are biological catalysts that increase the rate of chemical reactions by lowering the activation energy required for the reaction to occur.
However, enzymes have a finite capacity for substrate binding, and once all active sites are occupied, increasing the substrate concentration further will not increase the rate of the reaction. This is because the enzyme is already working at its maximum rate and cannot process any more substrate.
Therefore, increasing the concentration of reactants in an enzyme-catalyzed reaction can increase the reaction rate up to a certain point, but beyond that point, there will be no further increase in the reaction rate.
This concept is known as the enzyme saturation point and explains why increasing the substrate concentration beyond a certain point does not increase the reaction rate in enzyme-catalyzed reactions.