Answer:
Km as well.
Step-by-step explanation:
Km ( Michaelis constant) may be defined as the value or the substrate concentration at which half the reaction has. This permits the enzyme to achieve the half Vmax.
The turn over number may be defined as the ratio of the Kcat to the Km. The mutation that affects the turn over number of the enzyme will also affect the Kcat as well as Km. As the Km is also dependent on the turnover number of the enzyme.
Thus, the answer is Km.