Catalase Activity

Analysis

Graph 1 interprets the data shown on the table of results. The graph shows that the highest rate of reaction is at pH 7. This therefore supports my theory that at pH 7 the rate of reaction will be highest. This relate to other resources, such as books and the internet, which show that the optimum pH value for catalase is pH7, therefore there is no difference between the optimum pH and the pH used in the experiment, hence the enzyme structure is not affected by the pH and is most active.

However the graph inadequately supports the second part of the prediction, that the rate will be lowest, the more acidic or alkaline the pH level is. For instance when the rate starts of low on pH 4 (0.2) and starts to gradually increase. However it only increases until pH 5 (0.29), from that point, the rate decreases at pH 6 (0.116). Therefore the rate for pH 6 is an anomaly, as it does not follow the trend of the graph, by continuing to gradually increase, instead it decreases. According to my prediction, this rate is theoretically supposed to increase until pH 7, and then decrease again as it gets alkaline, however it does not, therefore this is an anomalous value, and will be discussed in the evaluation. The rate of reaction at pH 4 (0.2) is low because as the pH decreases, the high concentration of hydrogen ions bond with the hydrogen bond on the enzyme, therefore destabilising it by removing the bonds, so its 3D structure is affected, and according to the lock and key mechanism and induced fit model, then the enzyme is inactivated. The reason why the rate has not fallen to zero I because not all enzymes are denatured, the rate would continue to decrease until, eventually all the enzymes are denatured.

Similarly pH 9 has an anomalous value as the rate (0.84) is higher than the rate of pH8 (0.477). This again goes against my prediction, as the rate is supposed to decrease as the pH levels get more alkaline. As the pH levels increase from the optimum pH value then, the base (alkaline) conditions will affect the hydrogen bonds on the enzyme, and therefore destabilise the structure of the enzyme.

The shape of graph 2 shows how the trend should look like, by eliminating the anomalous results. In this graph it is clear to see that the rate of reaction starts of low at pH 4 and gradually increases until pH 7, and decreases after this point.

Evaluation

The experiment was a success to a certain extent. It showed that pH7 was the optimum pH level, where the enzyme can be most active and therefore have the highest rate of reaction.

The recording of all measurements carried out were carried out with maximum attention. However because the experiment was carried out cooperatively, it means that some groups may have put to use different practical techniques, which have affected the final results of the experiment. Therefore the recording of results was neither reliable nor precise. The timing, which measured the distance, the fluid travelled in the manometer, was always constant. It was always measured as soon as the hydrogen peroxide