pH

Every  enzyme  has  an  optimum  pH  at  that  the  rate  of  the  reaction  which  it catalyzes  is at its maximum.  Little deviations in pH from the optimum value lead to reduce activity due to changes in the ionization of collections at the active site of the enzyme.  Bigger  deviations  in  pH  lead  to  the  denaturation  of  the enzyme  protein  itself  due  to  interference  with  the  several  weak  noncovalent bonds maintaining its 3D structure. A graph of V0 plotted against pH will commonly give a bell-shaped curve. Various  enzymes  have  a pH optimum   of  approximate  6.8  but  there  is  great  diversity   in  the  pH  optima  of enzymes due to the dissimilar environments  in that they are adapted to work. For instance, the digestive enzyme pepsin is adapted to work at the acidic pH of the stomach around pH 2.0.