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The Effect of pH on the activity of enzyme Catalase

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Effect of pH on the activity of the enzyme catalase Riddhi Draksharapu The Effect of pH on the activity of enzyme Catalase Enzymes are globular proteins responsible for most of the chemical activities of living organisms. The pH at which enzymes function are extremely important. Hydrogen peroxide (H2O2) is toxic to most living organisms. H2O2 can be converted to oxygen and water, as follows: H2O2 2 H2O+O2 Although this reaction occurs spontaneously, enzymes increase the rate considerably. In this experiment, rate of enzyme activity was measured under different pH values. Hypothesis: 1. Most enzymes have an optimum pH near to 7. This is the optimum pH found inside most of the living cells. 2. pH is the measurement of the concentration of the Hydrogen ions (H+) 3. Hydrogen ion will affect the hydrogen and ionic bonds within the enzyme. 4. If these bonds are changed the three dimensional shape is changed altering the shape of the active site. ...read more.


Carefully add 10 pieces of the potato discs followed by 5cm3 hydrogen peroxide solution. 6. Place the bung back into the boiling tube as quickly as possible. 7. Start and stop watch and time how long it takes for the manometer fluid to rise by 5 cm. 8. Carefully agitate the tube to make sure that the potato discs do not stick together. 9. Wash out the boiling tube and repeat the experiment using different pH buffer and ten new potato discs each time. 10. Make sure you use a clean syringe/measuring cylinder with each different buffer solution. 11. Each reading is repeated thrice for increased reliability. 12. One control set up was set up with 5 cc hydrogen peroxide and time was measured to increase the level of the manometer fluid by 5cm. Data Collection and processing: Raw data: Results for control set up Table 2 pH (No pototo discs were added) Time taken for the manometer to move 5 cm (minutes) ...read more.


As pH2 was not close to the optimum pH for the enzyme catalase, the reaction rate was slow and pH 9 may be a little high for activity to bind the substrate with the active site. So we can see in these two pH that the amount of O2 production was not enough and time for the manometer fluid to raise 5 cm took more time. There are a few problems in my investigations I have faced that need to be minimised for the next experiment. They are discussed as follows: 1. Enzyme concentration of catalase varies with the age of the potato and even within the potatoes. 2. It was difficult for us to make the boiling tube air tight. Before the bung was inserted, there was a loss of gas from the test tube that could not be prevented. These problems could be overcome quite easily for the next time this experiment is conducted. To get the correct enzyme concentration, enzymes should be collected from the same part of the potato and there should be proper storage for the enzymes for at least two days prior to starting the experiment. ...read more.

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