Initial rate data for an enzyme that obeys Michaelis-Menten kinetics are shown i
ID: 1059707 • Letter: I
Question
Initial rate data for an enzyme that obeys Michaelis-Menten kinetics are shown in the following table. When the enzyme concentration is 3 nmol ml^-1, a Lineweaver-Burk plot of this data gives a line with a^/-intercept of 0.00426 (mu mol^-1 ml s). Part A Calculate k_Cat for the reaction. k_cat = 7.82 times 10^4 s^-1 Part B Calculate -K_M for the enzyme. Part C When the reactions in part (B) are repeated in the presence of 12 mu M of an uncompetitive inhibitor, the y-intercept of the Lineweaver-Burk plot is 0.352 (mu mol^-1ms). Calculate K'_1 for this inhibitor.Explanation / Answer
KM = 124 um
Vmax,apparent = 0.00426 umol/ml.s
Vmax = 0.352 umol/ml.s
Inhibitor [I} = 12 uM
So,
Vmax,apparent = Vamx/(1 + [I]/Ki)
0.00426 = 0.352/(1 + 12/Ki)
Ki = 0.147 uM