662 



14. EFFECTS OF pH ON ENZYME INHIBITION 



If piiC/ is plotted against pH, the slopes and inflection points will indicate 

 the pK„'s of the ionizing groups and the particular form of the compo- 

 nent that is ionizing. A similar treatment applies to the apparent maximal 



200- 



150 - 



100 - 



50- 



RATE 

 



7.5 



8.0 



PH- 



8.5 



Fig. 14.1. Shifts in the pH optimum for a-chymotrypsin produced by 

 increasing concentrations of methanol. (From Stein and Laidler, 1959.) 



rate when it is not equivalent to the true maximal rate and is given by an 

 expression such as: 



y.n = VJf,, (14-43) 



since: 



logF„/ =logF,„ -log/,, (14-44) 



and a plot of log VJ against pH will jn'ovide data on the ionization of the 

 ES complex. 



