pH

• All enzymes have an optimum pH or a pH at which they operate best
• Enzymes are denatured at extremes of pH

  • Hydrogen and ionic bonds hold the tertiary structure of the protein (ie. the enzyme) together
  • Below and above the optimum pH of an enzyme, solutions with an excess of H+ ions (acidic solutions) and OH- ions (alkaline solutions) can cause these bonds to break
  • The breaking of bonds alters the shape of the active site, which means enzyme-substrate complexes form less easily
  • Eventually, enzyme-substrate complexes can no longer form at all
  • At this point, complete denaturation of the enzyme has occurred
• Pepsin is an enzyme found in the stomach and it has an optimum pH of 2.