VARIATION OF ENZYME INHIBITION WITH pH 



687 



are not necessarily related to ionizations of the enzyme, inhibitor, or the 

 complex between them. 



It is usually difficult, if not impossible, to determine the type of inhi- 

 bition or to locate the ionizing groups from the pir/-pH curves alone, since 

 the curves for quite different systems may look alike. It is necessary to 

 elucidate the nature of the pH dependence of the uninhibited reaction and 



pH ► 



pH ^ 



Fig. 14-10 (continued) 



the basic mechanism of the inhibition before these curves can be inter- 

 preted and the ionizing groups specified. This is not to minimize the im- 

 portance of the Dixon treatment, which is a very valuable technique when 

 it is applied properly, but only to point out some of the complications in- 

 herent in its use in inhibition studies. 



Some illustrations of how the curves in Fig. 14-10 are derived from the 

 expressions for K/ in Table 14-1 may be given. The simple case in which 



