70 



3. KINETICS OF ENZYME INHIBITION 



From these equations one may obtain expressions for (E/) which determine 

 the boundaries: 



Ai 1 



Zone A - zone B: (E,') 



i (1 - i - Ai) (1 - i) 



i 1 



Zone B - zone C: (E/) = -- ^i r 



Ai \ — I 



(3-40) 

 (3-41) 



If we take the permissable error in the inhibition to be 10%, i.e. Aiji = 0.1, 

 the boundary curves in Fig. 3-11 are obtained. The boundaries are seen to 

 depend not only on (E/) but on the extent of inhibition or (I/). The vertical 

 lines are placed at 50% inhibition to indicate average values of (E/) that 

 may be taken as the boundaries between zones in most experimental pro- 



0.01 



100 



1000 



CE^)- 



Fig. 3-11. Zone boundaries for noncompetitive inhibition in a mutual depletion 



system. Aili = 0.1. 



cedures. Thus when (E',) reaches a value of 0.45 the system enters zone B; 

 at this point, if Michaelis-Menten equations are aj^plied, the per cent error 

 in the inhibition calculated will be 10%. When (E/) reaches 20 the system 

 will enter zone C. The tabulation below gives the boundary values for 



