effect of pH on amylase

• Digestion of starch solution into sugar solution using the enzyme amylase

  1. Prepare buffer solution at pH 5

  2. Repeat practical at pH 6, 6.4, 7, 8

  3. Control temperature conditions

  4. Measure temperature using water bath and thermometer

  5. Transfer 2 cm3 starch solution, 2 cm3 buffer solution, 1 cm3 enzyme solution into test tube

  6. Start timer immediately after mixing solutions

  7. Take 0 reading with iodine solution

  8. Repeat iodine test every 10 seconds

  9. Continue until no positive test for starch

  10. Count number of wells on spotting tile to get time taken for digestion
• Enzyme will start digesting the starch solution as soon as the solutions are mixed
• Colour change of iodine solution indicates presence of starch
• No colour change of iodine solution indicates all starch has been digested
• Optimum pH for amylase enzyme is expected to be around 7
• As time increases


  Colour change of iodine solution gets lighter
• pH of solution


  Affects rate of starch digestion by amylase
• Further investigation needed to find exact optimum pH for amylase
• Plotting rate of reaction against pH would show inverse relationship with optimum at pH 7