496 



10. EFFECTS OF MORE THAN ONE INHIBITOR 



to be predicted for the various types of inhibition discussed above. The 

 following relationships between (Ij)' and (Ig)' may be derived from Eq. 

 10-2 and i = I — vjv. 



-6 -7 



LOG CONC NEOSTIGMINE fM)- 



-8 



Fig. 10-3. Inhibition of human plasma cholinesterase by neostigmine 



alone and in the presence of 3.3 mM tetrapropylammonium ion (TPA). 



(From Foldes et al., 1960.) 



Both inhibitors competitive: 



(^/l - i)[(S)' + 1] - (I,)' 



dJ' = 



1 + [(l2)7«] 



Both inhibitors noncompetitive: 



^ (^/l - ^) - (I3)' 



^ '^ 1 + [(i.)7«] 



Ij competitive and L noncompetitive: 



[(S)' + l][(i/l -i) -(I.)'] 



(I.)' 



1 + [(i.)7«] 



(10-17) 



(10-18) 



(10-19) 



