The figure below shows the dependence of initial velocity, vo, on substrate concentration for an enzyme with a Michaelis constant equal to 3 x 10-4 M.
a. Calculate Vmax.
Choose a point from the graph. A convenient data pair (x,y) is (3 x 10-6, 2 x 10-6).
Remember the Michaelis-Menten equation:
but use the simplified form and use the following assumption given to you, [S] << Km.
vo = (Vmax/Km)[S]
Vmax = voKm/[S] = 2 x 10-6 M min-1 (3 x 10-4 M)/3 x 10-6 M = 2 x 10-4 M min-1
b. Is this the proper data region for evaluating Vmax?
No, we're evaluating Vmax in the 1st-order region, far from enzyme saturation.
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