What is the effect of enzyme saturation on reaction rates?

• A. Reaction rates become independent of substrate concentration
• B. Higher enzyme concentrations always lead to faster reactions
• C. Reaches a maximum rate at saturation level
• D. All enzymes lose activity at saturation

Answer: (C)

When considering the effect of enzyme saturation on reaction rates, the concept of maximum reaction rate is crucial. At low substrate concentrations, the rate of reaction increases linearly with increases in substrate concentration, as enzymes are readily available to bind with the substrate. However, as substrate levels continue to rise, a point is reached where all active sites of the enzyme molecules are occupied—a state known as saturation.

Once this saturation level is achieved, adding more substrate does not further increase the rate of reaction because the enzymes are already working at their maximum capacity. This maximum rate of reaction is referred to as Vmax. At this point, the reaction rates become independent of substrate concentration, as there are no unoccupied active sites available for additional substrates to bind. This illustrates that the correct understanding of enzyme saturation is that the reaction rates will reach a maximum as saturation is achieved, which aligns perfectly with the choice that indicates the achievement of maximum rate at saturation levels.