Effect of Temperature on Enzyme Activity

Experiment 1

Purpose of the experiment: the objective of this experiment is to investigate the effect of temperature on enzyme activity

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Hypothesis: Temperature has an effect on the enzyme activity

Prediction: There is an optimum temperature of enzyme activity beyond which activity drops.

Procedure

The experiment was conducted as per the procedures laid out in the lab manual

Setup: Determination of a temperature range in which the enzyme oxidase can catalyze its substrate. The optimum temperature of the reaction is also determined.

Materials:

Steps: 6 test tubes, china marker, test tube rack, metric ruler, heat resistant glove, wash bottle filled with 1% catechol, Celsius thermometer, ice bath containing wash bottle of potato extract which has catechol oxidase, three graduated beakers each of capacity 400mL.

Observations: At 0 min, the color intensity was light brown for all tubes. However, the absorbance changed with the increase in temperature.

Relative color intensity or absorbance

Test tube Tube 4A Tube 4B Tube 4C Tube 4D Tube 4E Tube 4F

Temperature 0C 21C 40C 60C 80C 100C

0 Min Light brown observed in all the tubes

5 Min 3 3 3 1 1 1

Table 1: Change in absorbance with time.

Fig 1: Graph showing relative color intensity at various temperatures.

Conclusion

This experiment shows that temperature has an effect on enzyme activity. Thus, the hypothesis can be accepted. Enzyme activity is high up to a point which it drastically drop. This experiment shows that optimum temperature is 40 degrees Celsius beyond which further increase or decrease in temperature leads to reduced enzyme activity. This proves the prediction is correct. To improve the outcome of the experiment in future, it would be necessary to use an accurate means of measuring relative color intensity.

Experiment 2

Effect of pH on Enzyme Activity

Purpose of the experiment: To investigate the effect of pH on enzyme activity

Hypothesis: pH has an effect on the enzyme activity

Prediction: There is an optimum pH beyond which enzyme activity drops.

Procedure

The experiment was conducted as per the procedures laid out in the lab manual

Setup: Determination of a pH range in which the enzyme oxidase can catalyze its substrate. The optimum pH of the reaction is also determined.

Materials:

Steps: 7 test tubes, china marker, test tube rack, metric ruler, china marker, wash bottle filled with 1% catechol, phosphate buffer (pH=2,4,6,7,8,10,12), ice bath containing wash bottle of potato extract which has catechol oxidase, vortex mixer.

Observations: The relative color of the test tube contents changed with various pH values.

Relative color intensity or absorbance

Test tube Tube 5A Tube 5B Tube 5C Tube 5D Tube 5E Tube 5G Tube 5H

pH pH2 pH4 pH6 pH7 pH8 pH10 pH12

0 Min Clear Cloudy Gold Brown Orange Brown Clear

10 Min Clear Yellow Gold Pink Pink Pinkish Clear

Conclusion 0.5 3 4.5 2.5 2 1.5 0.5

Table 1: Change in absorbance with various pH concentrations

Fig 1: Graph showing relative color intensity at different pH concentrations.

Conclusion

This experiment shows that pH has an effect on enzyme activity. The hypothesis can, therefore, be accepted. Enzyme activity is high up to a point which it drastically drop. This experiment shows that optimum pH for enzyme activity is 6. This is where further increase or decrease in pH leads to reduced enzyme activity. This proves the prediction correct. To improve the quality of results in future, it is necessary to have fractional values of relative color intensity. The values can be in fractions up to 2 decimal places.

Comparison of the Two Graphs

In experiment 1 Fig 1, the optimum temperature for enzyme activity is found to be 40 degrees Celsius. In Experiment 2 Fig 1, the optimum pH for enzyme activity is pH=6. This suggests a pH of 6 and at a temperature of 40 degrees, Celsius favors optimum enzyme activity.