The effect of substrate concentration on the rate of decomposition of Hydrogen Peroxide when catalysed by the enzyme Catalase.

Authors Avatar

Chemistry Coursework

The effect of substrate concentration on the rate of decomposition of Hydrogen Peroxide when catalysed by the enzyme Catalase.

Plan

In this experiment I have to investigate experimentally, the effect that substrate concentration has on the overall rate of decomposition of hydrogen peroxide when catalysed by the enzyme Catalase.

First I need to understand the hypothesis before starting the experiment. We have looked at the function of enzymes, the way they carry out reactions and also the effects of conditions on their reactions. Also the lock and key hypothesis, and the more recent induced fit model, enzyme- substrate complexes, and activation energies with and without enzymes, specificity and also the cause of denaturation of the enzyme.

In organisms, such as ourselves, Hydrogen Peroxide is a by product of our metabolism. The oxidations of certain cells in our body produce this toxic chemical. The chemical itself is pretty stable, and can last for prolonged periods of time in our body, and because of it’s toxicity, it must therefore be removed quickly. Catalase is the enzyme that will reduce the activation energy (energy needed to start a reaction), and increase the rate of the decomposition of Hydrogen Peroxide, so there is less chance of it intoxicating our cells.

In this experiment, the source of our Catalase enzyme will be potatoes. It works very quickly to reduce levels of Hydrogen Peroxide when present. It catalyses the decomposition of Hydrogen Peroxide by liberating Oxygen gas as effervescence. Catalase is also one of the fasting working known enzymes; each enzyme can produce 1012 molecules of oxygen per second by the decomposition of 40,000 Hydrogen Peroxide molecules per second at only 0 degrees Celsius.

The enzyme-substrate complex is the stage where the enzyme has joined with the substrate ready for the reaction to take place. The substrate must be of a particular size and shape to fit into the enzymes active site, once it has, the complex only lasts for a matter of seconds, and the products are formed. The induced fit model shows that the substrate molecule has a positive and negative charge either side, as does the active site of the enzyme, the attraction causes the formation of a complex, the enzyme then ‘squeezes’ on the substrate to produce more pressure, causing it’s bonds to weaken and break faster, forming the products. The equation for my experiment reaction is shown below:

Join now!

2H2O2+Enzyme                                2H2O+O2+Enzyme

Enzyme- Substrate Complex

Aim

Now that I have covered the functions of the enzyme, I am going to investigate certain factors that affect the rate at which Catalase can decompose Hydrogen Peroxide to Water and Oxygen. The factors that I have chosen to investigate are as follows:

  • Temperature
  • Substrate Concentration
  • Enzyme Concentration
  • pH Levels

I have chosen to study these four variables because they ...

This is a preview of the whole essay