The effect of temperature on the activity of amylase ne: Date due: gnature: Date

Question

The effect of temperature on the activity of amylase ne: Date due: gnature: Date: METHOD 1. Set up the thermostatic water bath at 40°C. 2. Light your Bunsen and heat the water bath to 60°C and 80°C (depending on the group) you may wish to get hot water from the main sink to speed things along. Take care. Set up 2 test tubes, one for the amylase and one for the starch. Do not forget to label them and add your initials. 3. 4. Use a syringe to place 5 ml of starch in one test tube 5. Place 5 ml of amylase solution into the second test tube using a second syringe. 6. Leave the two test tubes in the water bath until they have reached the designated 7. While waiting, put 3 drops of iodine (1/KI) solution into the wells of the spotting 8. At time zero, pour the starch solution into the amylase solution and mix them 9. After one minute, take a small sample of the mixture with the pipette and put 3 temperature (about 3 minutes). tiles together. Simultaneously start the stop elock. drops of the mixture into a well on the spotting tile containing already the 3 drops of iodine solution. Mix them by using a glass rod. Do not forget to clean the glass rod with distilled water between each sampling. Do not tura off the timer and do not remove the tube from the water bath 10. A fter two minutes, put 3 drops of the mixture into the second well of the spotting 11. Repeat at three, four and five minutes etc. putting 3 drops of the mixture into 12. Record the colour of the iodine. Continue for 10 minutes or until the sample appropriate wells. produces a yellowy-orange rather than blue-black color with the iodine solution = end point. 13. Count the minutes it has taken to reach the end point and record it. 14. Repeat the procedure at a range of different temperatures (0 C, 20°C, 40°C, 60°c and 80°C). Students could pool results to obtain replicate readings at each readings at each temperature For the room temperature study (20°C), record the real temperature. Rinse your tubes and spotting tiles with distilled water before starting a new investigation Be careful when you handle the test tubes at 40°C, 60°C and 80°C. Warning: Wear safety glasses when using a boiling water bath +Use a test tube holder. a) b) c)

Explanation / Answer

Discussion:

The activity of enzymes is dependent on temperature of the system. Increase in temperature results in increased collision of enzymes and substrate molecules. This leads to more number of molecules reaching the activation states thus overall rate of the reaction increases. Hence decreasing the temperature leads to reduced collision between substrate molecules leading to reduced enzyme activity. Hence decreased activity of amylase is observed at 00 & 200C temperature and more time is required to completely digest the starch.

Since enzymes are protein molecules that have a definite three dimensional structure that is stabilized with non covalent interactions. Increasing the temperature to a large extent will result in denaturation of the enzyme molecule and loss of enzyme activity. Thus decreased enzyme activity is observed at high temperatures(600C & 800C).

Thus enzymes are active at a narrow range of temperature known as optimum temperature, where the enzymes activity reaches maximal. For amylase, the optimum temperature is 370C hence increased activity of amylase is observed at 400C and less time is required to completely digest starch as compared to lower and higher temperatures. The plot between enzyme activity and temperature is usually bell shaped with highest activity observed at its optimum temperature and decreased activity at lower and higher temperatures.

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