GCSE Combined Science (AQA)

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Enzymes & pH

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Organisation Animal Tissues, Organs and Organ Systems

Enzymes & pH

3:02 Collision Theory and Rate of Reaction
Spec 4.2.2.1
Previous Enzymes & Temperature Next Rate of Chemical Reactions
  • The optimum pH for an enzyme is where its activity is highest.
  • Different enzymes have different optimum pH levels.
  • The pH scale ranges from 0 (very acidic) to 14 (very alkaline), with 7 being neutral.
  • Enzymes are placed on the pH scale around their optimum pH.
  • Stomach enzymes work best at an acidic pH, while intestinal enzymes work best at an alkaline pH.
  • Optimum pH is where the most successful collisions between enzyme active sites and substrate molecules occur.
  • Deviating from the optimum pH reduces enzyme activity.
  • A graph can show enzyme activity at different pH levels, typically peaking at the enzyme's optimum pH.
  • Moving away from the optimum pH decreases enzyme activity.
  • Extreme pH conditions can denature enzymes, altering the shape of their active sites and preventing substrate binding.
  • Denaturation from extreme pH is permanent and damages the enzyme's structure, making it unable to bind to its substrate.

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