Mode of inhibition. The kinetics of an enzyme are measured as a function of substrate concentration in the presence

and in the absence of 2 mM inhibitor (I).

S 3 5 10 30 90

No inhibitor 10.4 14.5 22.5 33.8 40.5

inhibitor 4.1 6.4 11.3 22.6 33.8

(a) What are the values of V max and K M in the absence of inhibitor? In its presence?

(b) What type of inhibition is it?

(c) What is the binding constant of this inhibitor?

(d) If [S] = 10 mM and [I] = 2 mM, what fraction of the enzyme molecules have a bound substrate? A bound

inhibitor?

(e) If [S] = 30 mM, what fraction of the enzyme molecules have a bound substrate in the presence and in the absence

of 2 mM inhibitor? Compare this ratio with the ratio of the reaction velocities under the same conditions