• Large beaker (to use as a water bath)
• Access to varied temperatures of water/water bath
To do this we will be using a simple experiment which evolves using hydrogen peroxide and potato extract which contains vast amounts of catalase. Variables that could have an affect on this experiment are:
• Concentration of the catalase
• Temperature
• Surface area of the filter paper
• Amount of hydrogen peroxide
The variable we are going investigate will be the temperature. Variables we will have to keep the same will be.
• Surface area of the filter paper
• Amount of hydrogen peroxide
• Concentration of catalase
I predict that the closer the temperature to body temperature the more efficiently the enzyme will work. I predict this because if the enzyme was made for the use in the body then it should be best suited to working in the body’s conditions.
Investigating the Effect of Temperature on the Enzyme Catalase
Safety
hydrogen peroxide is a bleach and will burn skin, eyes ect. to conduct this experiment safely we will be wearing goggles at all time, and taking care when handling beakers test tubes containing hydrogen peroxide.
The Experiment
The experiment goes as follows: First we cut up 15 pieces of filter paper each measuring 1cm2. Then filled a 100ml beaker with 60ml of hydrogen peroxide. Now we put a test tube of the potato extract in a water bath until it reached the required temperature. Then using tweezers we dipped one of the 1cm2 squares of filter paper in the extract and then tapped it once to remove any excess. Then we dropped the piece of filter paper in the hydrogen peroxide and as soon as it hit the bottom of the beaker we started the stopwatch. Then because of the reaction going on which I will explain later, oxygen bubbles form and lift the piece of filter paper back to the surface. When the filter paper reaches the surface we then stopped the clock.
Now with our first few experiments that we did, we just heated the potato extract but left the Hydrogen peroxide at room temperature. This proved to give very similar results even with different temperatures. So we then decided to heat both the potato extract and the Hydrogen Peroxide which proved to be much more successful.
Explanation Behind the Experiment
The reason behind the filter paper floating back to the surface is, that when the catalase is added to the H202 it breaks down a bond in the compound leaving you with H20 and 0 (water and oxygen). The oxygen is formed above and below the filter paper but gets trapped underneath. When enough oxygen has gathered underneath the filter paper it then rises back to the surface.
Investigating the Effect of Temperature on the Enzyme Catalase
Preliminary experiment
After having done eight experiments we realised that just heating the enzyme would not be enough, because as soon as we dropped the filter paper in the hydrogen peroxide it would cool straight back down to room temperature. So we then repeated the experiment heating both the hydrogen peroxide and the enzyme.
Second set of results
Results for the time taken for the filter paper to rise to the surface
Investigating the Effect of Temperature on the Enzyme Catalase
Analysis of the results
From the results I have noticed that the speed which it takes for the filter paper to rise back to the surface increase’s around body temperature then starts to go a little faster at 50°C then slows dramatically at 60°C. The reason behind this, is that when a enzyme gets to a certain temperature it will de-nature (go out of shape). And when this happens the substrate no longer fits the active site and the breaking down of molecules will not continue. But at 60°C not all of the enzymes have been denatured so the reaction still works just not as quickly as at temperatures closer to body temp (37°C).
Now that the enzyme has been denatured the substrate won’t fit into the active site because it has been deformed.
Conclusion
My graph begins to fall at a steady rate although the result for 30oC could have been slightly slower so it fitted the curve. At 60oC the graph then shoots up indicating that the enzyme had been denatured. From my results I conclude that catalase’s optimum temperature to work at is around the 50°C. The reason behind this is that the hydrogen peroxide molecules will be moving about faster, therefore more molecules will come into contact with the enzyme. And because the temperature isn’t too high the enzymes won’t de-nature. My prediction was that the enzyme would work best around body temperature then get worse, which wasn’t to far of my results.
Evaluation
The way in which we conducted the experiment was reasonably controlled but the amount of catalase on the filter paper could have varied slightly.
Investigating the Effect of Temperature on the Enzyme Catalase
The procedure could have also been improved by using fresh H2O2 with each experiment, because some of the hydrogen peroxide will have been broken down into oxygen and water. This would have then diluted the hydrogen peroxide. Overall the procedure gave reasonably reliable result with some anomalies that didn’t affect the average too much. Further experiments could involve trying lower and higher temperatures, to see which temperature the enzyme would work most efficiently at and what temperature the enzyme becomes fully denatured at. Also if I were to repeat the experiment I would do more repeats of each experiment to make the average more accurate. Testing with smaller gaps in temperatures i.e. 5oC gaps rather then 10oC gaps. Would show more precisely when the enzyme becomes denatured and when it’s at its most efficient. Also the use of a water-bath would have given more accurate results, because it can keep things at a constant set temperature.
