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The Effect of pH on the activity of catalase.

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Dereje Mengiostu Work partners Sana & Derek Date3rd Nov The Effect of pH on the activity of catalase Introduction Enzymes are sensitive to pH i.e. they have a specific pH in which they can work best. Some work best in acidic medium while others work best in basic medium - yet others are more active in neutral medium. In this experiment we tried to investigate the effect of pH on the activity of catalase. Catalase is a respiratory enzyme that breaks down H2O2 which is produced by cellular respiration as a bi product. Catalase breaks down it in to water and oxygen gas. As every enzyme the activity of catalase is highly influenced by variation of pH. From theory we know that it works best at the pH value of 9. What is the ideal pH for catalase to work best? Apparatuses and chemicals used in the experiment * HCl acid to increase acidity of the substrate * NaOH to give the substrate a basic nature * Diluted H2O2 as a substrate to be acted upon by catalyse * Blundered liver as a source ...read more.


12drops of NaOH 9.3 77 101 89 4. 3 drops of HCl +9 drops of H2O 1.9 5 6 5.5 5. 3 drops of NaOH + 9 drops of H2O 8.6 125 127 126 6. 9 drops of HCl +3 drops of H2O 1.7 3 3 3 Discussion In this particular experiment we have used the same amount of H2O2 (20 ml) and blundered liver (0.5 ml) that contains naturally made catalase produced by liver cells through out the experiment but we had to change the pH level by varying number of drops of NaOH base, HCl acid & H2O in each trial as indicated above in the table of results. Though I do not dare to say our experiment is quite precise as it should be we could get a result which is very close to the theoretical ideal pH for catalase. We could prove that the activity of catalase is highest around the pH 9. From our 2nd trial we could get 121.5 cm3 of gas in average at the pH value of 9. ...read more.


The gas syringe was not big enough to hold the gas produced in some cases and we had to open the baker to let out the gas from the gas syringe to make it ready to measure the remaining gas produced from the reaction. This time some amount of gas has escaped. We have used 0.5 cm3 of blundered liver but we could use even smaller amount of liver to get more accurate result since we could get lesser amount of gas that could be measured easily. The problem is the uncertainty of the syringe we have used is high and it is more difficult to measure very small amount of the blundered liver with it accurately but we could have overcome this problem if we had used a syringe with lesser uncertainty or we had use bigger gas syringe if there was. I think if we had better pH measuring device or universal indicator we could get more accurate result. If we could use burette or pipette to measure the volume of H2O2 than using measuring cylinder we could get better result since these two apparatuses have lesser uncertainty. ...read more.

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