Final answer:
The maximum velocity (Vmax) in an enzyme-catalyzed reaction is determined by the enzyme's saturation rate with the substrate (Km) and the intrinsic catalytic rate when all active sites are occupied (kcat).
Step-by-step explanation:
The maximum velocity (Vmax) at which a saturated enzyme-catalyzed reaction converts substrate to product is determined by two main properties:
- The rate at which the enzyme becomes saturated with the substrate is related to Km, which is the Michaelis-Menten constant. The Km value represents the substrate concentration at which the reaction rate is half of the Vmax.
- The intrinsic catalytic rate of the enzyme when all active sites are saturated, also referred to as kcat or the turnover number, which is directly related to the Vmax as it describes the maximum rate of the catalyzed reaction.
In an enzymatic reaction, with all other conditions constant, increasing substrate concentration ([S]) will increase the rate of product formation until it reaches a point where further increases in [S] do not increase the initial rate of reaction. This saturation point reflects when all enzyme active sites are occupied, resulting in Vmax being achieved and the intrinsic catalytic properties of the enzyme determining the turnover rate.