Enzymes are proteins that speed up many chemical reactions in cells. They act on substrates. Each enzyme acts only on specific substrates. Also it might be a reaction between a specific combination of substrates and a specific enzyme. Enzymes affect the rate of almost all chemical reactions which take place in organisms. Like all other proteins, enzyme function may be affected by a change in any aspect of its structure. The effect of a change in enzyme structure is called denaturation. Some substrates fit in the active site of the enzymes, but they are not taken apart by enzymes.They don?t let enzyme, which they occupied, take part in reactions anymore. They are called inhibitors.
The activity of enzymes is affected by pH, by temperature, presence of inhibitors, enzyme concentration and substrate concentration. There are still large areas of medical research in which the diagnostic potential of enzyme reactions has not been explored at all.
Catalase is an enzyme which is produced by every cell to break down hydrogen peroxide. Catalase is located in a cell organelle called the peroxisome. Hydrogen peroxide is a waste product of cellular activity that is poisonous to cells. However, it was used for a long time as a wound treatment (Some Eastern European countries still use it). Catalase speeds up the decomposition of hydrogen peroxide into harmless water and oxygen gas.
Catalase enzyme activity (measured as % of oxygen produced)
1 experiment: pH 2 experiment: temperature
Amount of time
The purpose of this lab was to determine the effect of pH and temperature on the rate of catalase enzyme activity. Since the catalase speeds up the decomposition of hydrogen, the rate of catalase activity was measured indirectly by measuring the change in % oxygen produced over a fixed time period.
There were two experiments perfromed. First one determined the dependence of rate of catalase activity on the level of pH. In the first experiment our hypothesis was that if the level of pH decreases, then the rate of hydrogen peroxide degradation decreases. The second experiment investigated the effect of temperature on catalase activity. In the second experiment our hypothesis was that if the temperature decreases, then the speed of hydrogen peroxide decomposition decreases.
Materials and Methods:
Since hydrogen peroxide is potentially damaging to skin and eyes, goggles were worn for the duration of the experiment.
A Vernier? Oxygen Gas Sensor probe was connected to a Vernier Logger Pro? data collector, the apparatus was checked to confirm that it was working correctly.
200 ml of catalase solution was prepared by mixing 25 g of COOP? yeast into lukewarm distilled water.
Experiment 1: Effect of pH on the rate of decomposition of hydrogen peroxide:
The first experiment investigated the effect of pH change on the rate...