According to the Michaelis-Menten model, what does Vmax equal?

In the context of enzyme kinetics described by the Michaelis-Menten model, Vmax represents the maximum rate of an enzymatic reaction when the enzyme is saturated with substrate. This saturation means that all active sites of the enzyme molecules are occupied, leading to the maximal turnover rate.

Vmax is mathematically defined as the product of the catalytic rate constant (kcat) and the total concentration of enzyme available ([E]total). kcat essentially tells you how many substrate molecules can be converted to product by one enzyme molecule per unit time when the enzyme is fully saturated with substrate. Thus, when multiplying kcat by the total enzyme concentration, you obtain the maximum reaction rate (Vmax).

This relationship is fundamental for understanding enzymatic reactions, as it helps define the capacity of the enzyme to catalyze reactions under optimal conditions. An increase in the concentration of the enzyme (while keeping other parameters constant) will proportionally increase Vmax, illustrating that more enzyme availability allows for a higher maximum reaction rate.