Final answer:
The maximum capacity at which an enzyme works is when its active sites are saturated, and the corresponding reaction velocity is known as Vmax. The Michaelis-Menten constant, Km, is another kinetic factor indicating the enzyme's substrate affinity.
Step-by-step explanation:
The question pertains to the conditions at which an enzyme is working at maximum capacity, and the velocity at saturation is referred to as Vmax. In enzymatic reactions, increasing the substrate concentration ([S]) leads to a higher rate of product formation until all active sites of the enzyme are saturated with the substrate. At this saturation point, the enzyme operates at maximum velocity, which is Vmax. The Michaelis-Menten constant, Km, is the substrate concentration at which the reaction rate is at half of Vmax. This signifies the enzyme's affinity towards the substrate and is a key kinetic factor alongside Vmax in characterizing enzyme kinetics.