The figure below shows the dependence
of initial velocity, v_{o}, on substrate concentration
for an enzyme with a Michaelis constant equal to 3 x 10^{-4}
M.

a. Calculate V_{max}.

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] << K_{m}.

So:

v_{o} = (V_{max}/K_{m})[S]

V_{max} = v_{o}K_{m}/[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 V_{max}?

No, we're evaluating V_{max}
in the 1st-order region, far from enzyme saturation.

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