Investigating enzymes

• You can use continuous sampling to find the time taken to digest starch at different PH values.
• Aim of investigating enzymes - to investigate the effect of PH on amylase activity ( amylase is an enzyme that breaks down starch into simple sugars )
• Method of investigating enzymes:

  1. Add 1 drop of iodine solution to a well in all spotting tiles - all the solutions should be at the same temperature
  2. Into a test tube add : 2 cm³ of PH buffer , 2 cm³ of amylase solution and 2 cm³ of starch solution
  3. Mix with a glass rod and start a stopwatch
  4. After 30 seconds , use the glass rod to transfer 1 drop to the well in the spotting tile
  5. Repeat step 4 until there is no change in colour of the iodine solution stop the clock and record the time
  6. Repeat steps 1 - 5 using different PH buffer solutions
• How can we keep the solutions at the same temperature?

  Put them in a water bath of 25 °
• What does a buffer solution do?

  resists changes to its PH
• When the iodine no longer changes colour there is no starch present - it has all become digested to simple sugars
• The optimum PH is the greatest rate of reaction
• rate ( / s ) = 1

  -----------

  time ( s )

  For example if the reaction time is 200 seconds reaction rate = 1 / 200 = 0.005 / s