DISSOCIATION OF THE ENZYME-INHIBITOR COMPLEX 



609 



where i^ is the initial inhibition and ij is the final equilibrium inhibition, 

 i/ depending on (I^) in a manner characteristic of the inhibition. This equa- 

 tion reduces to Eq. 13-4 when (If) = if = 0. Equation 13-8 is plotted in 

 Fig. 13-1 for various values of (I^) and it may be noted that the rate of 

 inhibition reversal depends, as expected, on the magnitude of the decrease 

 in inhibition, (?o — if)- The time required for the inhibition to fall half 



TIME 



Fig. 13-1. Rates of decrease of inhibition when the inhibitor concentration is sud- 

 denly reduced to various levels (Eq. 13-8). (l)^ = 5 mM, K^ = 1 mil/, A-_i = 0.1, 

 and i^ = 0.833. Curve A: (I^) = 3 mil, t^.^ = 1.73; curve B: (I,) = 1 mM; t^.^ = 3.46; 

 curve C: (I,) = 0, t^.^ = 6.93. 



the way to its eventual level, t^ 5, increases as (I^) is reduced, since from 

 Eq. 13-8: 



and the time required to reach final inhibition levels varies in a similar 

 fashion. That is, it requires more time to reach equilibrium when the fall 

 in the inhibition is large than w4ien small, even though the rate at which 

 the inhibition falls is greater in the former case. 



Let us for a moment consider the effects of dilution upon inhibition in 

 various systems. The results will depend on whether the inhibition is 



