Investigation of the effect of temperature on the action of peroxidase enzyme to decompose hydrogen peroxide

                                                                20

                                                                10

        Control

                Amount of peroxidase (10ml)

                Amount of hydrogen peroxide (20ml)

                Length of experiment (2min)

                Time between measurements (15sec)

                Equipment used

Safety

        I will keep my safety goggles on at all times to prevent painful eye injury.

Method

        For accuracy I am using six different temperatures and I will repeat the whole experiment twice.

        I will record my results in a table. I will then transfer those figures into two line graphs showing gas given off against time. Using these I can  then work out the rates of reaction for both experiments and find the averages from the results. Taking the averages I will plot them against the temperatures the experiments were conducted at. By doing this I can finds the temperatures that peroxidase works best at.

Doing the experiment

1. Set up the equipment as shown in the diagram.
2. Heat the peroxidase and hydrogen peroxide separately to the required temperature.
3. Mix the hydrogen peroxide and the peroxidase in a conical flask, replace the bung quickly.
4. Begin timing.
5. Record the amount of gas given off every fifteen seconds.
6. Repeat for different temperatures.
7. Repeat the whole experiment.
8. Make two line graphs for both experiments.
9. Work out the rates of reaction for each temperature, make an average for both experiments.
10. Plot the average rates of reaction against the temperatures the experiment was conducted at.

Prediction

My prediction is that peroxidase will work best at body temperature.

        In my preliminary experiments I discovered this reaction doesn’t coincide with the collision theory. I found this because if you heat up the reactants the reaction is slower.

        Using the theory that enzymes are sensitive to temperature, cooling the enzymes slows down the reaction. When they warm up again they continue to work at their normal speed. Over heating permanently damages the enzymes because they change shape or become denatured.

As the temperature rises, so does enzyme activity – until the enzyme becomes denatured then its activity falls suddenly to a zero.

Analysing

I discovered that if you make the temperature of the reactants, the rate of reaction decreases therefore if you decrease the rate of reaction the temperature of the reactants goes down. If you increase the temperature of reactants the rate of reaction gets faster and faster until it suddenly slows down.

This means that the enzymes are temperature sensitive and cooling the down slows them. But heating them up keeps them working at the normal speed. If you over heat the enzymes the become denatured (this means they are permanently damaged) they do not die.

When you rise the temperature it makes the enzymes work harder and faster.

This means my prediction was right.

Evaluation

Our results were a bit off but we didn’t have any really bad ones, they fact that they weren’t that good was because of the reactants being the wrong temperature. Or the gas not being read properly. Or the fact that there was already some air in the measuring cylinder.

        The experiment couldn’t really have been improved but it could have been more efficient. Like we could have been more careful at reading the results and putting the water filled measuring cylinder in the trough.

        I think my results were correct because the look right on the graphs (there are no anomalous results)

        If I was to do this experiment again I would make the temperature band smaller in order to find the temperature at which the enzymes are denatured  , something like between 34 and 43 degrees. This is because my graphs suggest that it be between those to temperatures at which the enzymes denature.