35. The activity of both enzymes declines
on both sides of their respective optimal pHs because as they are exposed to
either more acidic (lower pHs) or more basic (higher pHs) conditions, the enzyme
structures begin to denature. If the active sites on these two enzymes are deformed
enough, they become unable to recognize and bind their respective substrates
and the reactions they catalyze cease to occur.
--------- ---------
Slichter