Final answer:
Changing the Michaelis-Menten constant Km to 0.2 would mean that a lower substrate concentration is needed for the enzyme to reach half of its maximum velocity Vm. However, Vm itself would remain unaffected as it is independent of Km.
Step-by-step explanation:
The question asks about the consequences of changing the Michaelis-Menten constant (Km) to 0.2 on Vm, which is the maximum velocity in an enzyme-catalyzed reaction as described by the Michaelis-Menten kinetics. The Km is a measure of the substrate concentration needed to reach half of Vm. In the Michaelis-Menten equation, V = Vm [S]/(Km + [S]), the change in Km affects how easily the enzyme becomes saturated with substrate and thus, how quickly Vm is approached.
When Km is decreased to 0.2, it implies that a lower concentration of substrate is needed to reach half of the maximum velocity (Vm) compared to a higher Km value. This typically indicates that the enzyme has a higher affinity for the substrate. However, Vm itself represents the theoretical maximum rate of the reaction when the enzyme is fully saturated with substrate, and it is actually independent of Km. Thus, changing Km would not affect Vm directly but would indicate that the enzyme reaches its half-maximal velocity at a lower substrate concentration.