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Investigating the factors affecting peroxidase enzyme activity

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Investigating the factors affecting peroxidase enzyme activity Aim In this experiment I aim to investigate the factors which affect enzyme activity. I will be using hydrogen peroxide and peroxidase enzymes from an avocado. Background information Enzymes are used to break down a substrate e.g. fat, in an organism. They do this using the lock-and-key theory. This means that the enzyme has a specific shape and size with something called an 'active site' in it. Th active site is like a chunk taken out the enzyme, in which only the substrate it is designed to break down will fit. Enzymes are held together by bonds which form the shape of the active site. This is why a cell can become 'denatured'. This happens when the bonds break and the shape of the active site is changed. The enzyme will never regain its original shape, and as the substrate will no longer fit into it. ...read more.


experiment accurately * A measuring cylinder to measure the amount of oxygen released during the reaction * Delivery tubes * Trough * A thermometer so I can change the temperature accurately * Rubber stoppers * Goggles and other safety equipment Method 1. First of all I will set up the apparatus as they appear in the diagram. 2. I will place 30ml of 5% Hydrogen peroxide solution in the conical flask & add 2ml of the 5% peroxidase solution. Then I will quickly place a rubber stopper on the flask. 3. Now I will follow the reaction at different temperatures to get a good range of results. The temperatures I will be using are 0�c, 20�c, 40�c, 60�c and 80�c. I have chosen these temperatures because preliminary experiments have shown that the reaction works at a reasonable speed with this steady increase. 4. Before I add the avocado extract I will stir the solution to ensure that there is an even distribution of the enzyme. ...read more.


At 0�C the initial rate of reaction was 8 cm /min. At the optimal temperature the initial rate of reaction was 174 cm /min. My results confirm my prediction, the rate of reaction was highest at the optimal temperature. However, they did not double for every 10� rise in temperature. Evaluation I think that the method was a good one, and reliable as it was repeated. It was not too hard to set up and carry out so there is a reduced chance of making a major mistake. I could have improved the experiment collecting the gas in a syringe instead of a cylinder as there would be less chance of any gas escaping. I could have kept the enzyme and substrate in a water bath for longer to ensure that they were at the correct temperature. I could have left more time for the enzyme to be denatured. The reliability could also have been improved by repeating the experiment more times and trying a wider range of temperatures. I if had used ph buffers I could have made sure the ph level was always stable. ...read more.

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