CONCENTRATION-TIME CURVES FOR INHIBITION 



601 



would not conform so simply and: 



(IK 



h 



K,t 



(12-94) 



Since if usually is dependent on (I) and t occurs on the right side of the 

 equation, the log-log plot will not be linear. This deviation from linearity 



LOG 



ni)-ll)r^ 

 (mM) 



-0.5 



LOG f (HOURS) 



Fig. 12-43. Log-log plots of the concentration-time curves for 

 the killing for tjiianosomes by various arsenicals. Time for 

 90° o mortality. (From Hawking. 1938.) Curve A, arsenite; 

 curve B. Xeoarsphenamine; curve C, reduced tryiiarsamide; 

 curve D, phenylarsenoxide. 



is shown in Fig. 12-44, where curve A represents an irreversibile inhibition 

 and curve B a similar reversible inhibition. The deviation occurs principally 

 at lower inhibitor concentrations where K^ contributes to the exponential 

 factor in Eq. 12-93 and the final inhibition does not approach completion. 

 In competitive inhibition, further complications arise, and there are many 

 other reasons for the kinetics to deviate from the simple (I)"^ = C type of 

 equation. If enzyme inhibition itself is capable of presenting so many dif- 

 ferent sorts of behavior, it would be expected that cellular inhibition ki- 



