VARIATION OF ENZYME INHIBITION WTIH pH 



" The types of inhibition are classified as earlier in the chapter and the reaction 

 schemes are indicated where possible. Evaluation of K/ is as follows: type A plot, 

 from slope; type D plot, from slope; type F plot, from intercept. It is assumed that 

 K/ is evaluated as if no ionization occurred. 



only the inhibitor ionizes and the I form is active (Case I a) provides the 

 expected value for K/: 



(H) 



Taking the logarithm of both sides: 

 pZ,' = pKi - log 



A' 



Ki 



1 + 



(H) 



(14-110) 



(U-iii; 



When the pH is in a range significantly lower than the vK,,. the term (H) i^^ 

 will be much greater than one and thus: 



Low pH: pA'/ = pA, + pH — pA^ 



(14-112) 



When the pH is significantly higher than the pA^^, the term (H)/A^ is 

 negligible compared to one and thus: 



High pH: pA/ = pA, (14-113) 



Therefore, in the low pH range the curve will have a slope of + 1 but will 



