pH

• pH is a measure of acidity
• a graph showing the rate of enzyme reaction changing with pH

  
• if the pH gets too high or too low then it will lower the rate of reaction because some of the bonds holding the enzyme together start to break so the active site will start to change shape. if the active site changes to much the substrate would not be able to fit into the active site so the enzyme has been denatured
• optimal pH

  the pH at which the enzyme works best at and depends where the enzyme normally works. most enzymes in the body work best at neutral pH at around 7 but the ones that work in the stomach have an optimal pH of around 2 as they need to be able to function in the stomach acidic environment