4. Enzymes and pH

• 1. Label a test tube with the first value of pH buffer solution (pH4) and stand on the rack
  2. In each spotting tile add a drop of iodine solution
  3. Using a measuring cylinder, measure 2cm^3 of amylase and pour into the test tube
  4. Using a syringe, measure 1cm^3 of the buffer solution and pour into test tube.
  5. Leave this to stand for 5 minutes and then use a thermometer to measure the temperature. Make a note
• 6. Add 2cm^3 of starch solution into the test tube, using a different measuring cylinder to measure, and begin a timer

  7. After 10 seconds, use a pipette to extract some of the amylase solution, and place one drop into the first well of spotting tile and put remaining back in the tube

  8. Continue to place one drop in each well, every 10 secs, until the iodine remains orange

  9. Record time take for starch to be digested by counting the amount of wells (each well represents 10 seconds of time)

  10. Repeat for pH values 7 and 10