In a Michaelis-Menten graph, what is represented on the x-axis?

In a Michaelis-Menten graph, the x-axis represents substrate concentration. This choice is foundational to understanding enzyme kinetics, as the relationship between substrate concentration and the rate of enzyme-catalyzed reactions is what the Michaelis-Menten model describes.

As substrate concentration increases, more substrate is available for the enzyme to bind with, leading to an increase in the rate of reaction, which is reflected on the y-axis. The graph typically reveals a hyperbolic relationship where, at low substrate concentrations, the reaction rate increases linearly with increasing substrate. However, as the substrate concentration continues to rise, the reaction rate approaches a maximum velocity (Vmax), indicating that all enzyme active sites are occupied, and the enzyme is saturated with substrate.

This understanding of how substrate concentration affects the rate of reaction is crucial for predicting and manipulating enzyme behavior in various biological and biochemical contexts.