The Investigation of Catalase With Hydrogen Peroxide

Authors Avatar

The Investigation of Catalase With Hydrogen Peroxide

Introduction:

Hydrogen Peroxide is a toxic chemical, produced by many living organisms as a product of the biochemical reactions occurring in the cells. As hydrogen peroxide is poisonous it must be removed quickly. The enzyme catalase speeds up the reaction that breaks down hydrogen peroxide into water and oxygen.

            Catalase

H2O2  ------------------------> H2O + O2 

Catalase can be found in potato cells. When hydrogen peroxide is added to the potato as a liquid, the catalase in the potato breaks down the hydrogen peroxide into water and oxygen – two substances which are essential for our bodies. Therefore catalase is essential in our bodies to break down H2O2.

Aim:

The aim is to think about what factors affect the rate of enzyme (catalase) reaction. My aim will be the investigation of the relationship between the enzyme concentration found in the potato and the rate of reaction of the enzyme catalase with the hydrogen peroxide.

Hypothesis:

Enzymes are proteins that are made in cells, which act as catalysts. A catalyst is a chemical substance that speeds up reactions without being used up itself so it can be used more than once. They speed up the rate of reaction by lowering the activation energy; the energy required to break the bonds of the substrate. Enzymes have a complex and specific shape and they catalyse reactions by forming a complex, called the enzyme substrate complex, at a specific region of the enzyme called the active site. Enzymes are specific; an individual enzyme can only catalyse one particular reaction. The induced fit hypothesis explains how enzymes work.

When the substrate approaches the active site of the enzyme, the shape of the active site changes to fit precisely around the substrate; the substrate induces the active site to change shape. The reaction is catalysed and the products are formed. The products are a different shape from the substrate so they diffuse away from the active site. The active site reverts to its original shape as the diffusion takes place.

Enzymes work at different rates in different conditions. What this means is that when catalase is working quickly, it will break down several times more hydrogen peroxide molecules per second than when it is working slowly. The speeds of the reactions are dictated by different factors.

Temperature affects the rate at which enzymes work. The temperature at which enzymes work at their best is known as the optimum temperature. In general, a rise in temperature increases the rate of reaction; a fall in temperature slows the reaction rate. The rise in temperature increases kinetic energy, thus increasing the chances of collisions of the substrate with the enzyme’s active site. However if the temperature is too high or too low enzymes lose their shape become denatured and do not function.

The pH balance affects the rate of reaction. The optimum pH is the pH at which the enzyme works best. Most enzymes work best in neutral conditions (pH 7), except in the stomach, where the enzymes work at pH2.

The concentration of substrate molecules also affects the rate of reaction. An increase of substrate molecules (hydrogen peroxide) will increase the rate of reaction because there are more substrate molecules to occupy the available sites of the potato catalase. However a constant increase in substrate molecules will have no effect on the rate of reaction because the substrate molecules will occupy all the available sites of the catalase. Therefore I need to keep the concentration of substrate molecules the same.

Join now!

The concentration of enzyme (the one I am investigating) also affects the rate of reaction. A higher concentration of enzyme increases the reaction rate because the numbers of active sites of the enzyme are increased. There are more available active sites for the substrate to get in contact with and for the induced fit hypothesis to take place. The substrate has a higher chance of inducing an active site because there are more available sites. They are more spread out and have an increased surface area.

Lowering the enzyme concentration will decrease the number of active sites available therefore ...

This is a preview of the whole essay