How does substrate concentration affect the velocity of an enzyme-catalyzed reaction according to the Michaelis-Menten model?

According to the Michaelis-Menten model, as substrate concentration increases, the velocity of an enzyme-catalyzed reaction also increases until it reaches a maximum velocity (Vmax). The reaction velocity is most sensitive to changes in substrate concentration when the concentration is below the enzyme's Km, where small increases in substrate can significantly enhance the reaction rate. Once substrate concentration exceeds Km, further increases have a diminishing effect on velocity.

The Michaelis-Menten equation describes the relationship between substrate concentration and the initial velocity of an enzyme-catalyzed reaction. At low substrate concentrations, the reaction rate increases proportionally with substrate concentration. However, as substrate concentration approaches and exceeds the Km, the reaction velocity approaches Vmax, and the effect of additional substrate on the reaction rate diminishes. This phenomenon is known as saturation kinetics, where the enzyme becomes saturated with substrate, and all active sites are occupied, limiting further increases in reaction velocity.