Effect of Temperature on Rate of Reaction of Catalase

Effect of Temperature on Rate of Reaction of Catalase
Introduction This investigation was in an attempt to try to find out how varying the temperature can affect an enzyme. The enzyme used was catalase which breaks down Hydrogen Peroxide, this gives off water and oxygen as effervescence. This effervescence is what is used to measure the reaction rate of the catalase. The optimal heat for enzyme activity is proven to be 37oC as anything above this denatures the enzyme. Denaturing is where the heat energy of breaks down the di-sulphide, ionic and hydrogen bonds that hold the tertiary structure together, this in turn changes the shape of the active site and so halts any reactions that the enzyme would otherwise be able to catalyze.
Method 6 test tubes were set up and 2cm squared of Hydrogen Peroxide was placed in each tube. Each tube was then placed in a water bath of the corresponding temperature (20oC, 40oC, 60oC and 80oC), and one in a beaker of ice (0oC). They were all left in for 10 minutes to take them all to the desired temperature before the experiment began.6 strips of potatoes were then cut to 1cm3 using a ruler and scalpel. One of the strips was put into each tube and then timed with a stop clock and the level of froth was measured as it rose up the side of the tube every 20 seconds until the froth started to fall. This was done to each tube individually so that a more accurate measurement was taken. Results See Overleaf. Conclusion The enzymes were at low activity at around 0oC and then a slight rise all the way up to 40oC (gentle curve), followed by a steep downward curve or slow in activity up to 60oC then a very strange rise in activity at 80oC. Discussion As the temperature rose the particles began to vibrate faster, this is turn caused more collisions between particles. This is why the reaction rate rose with the temperature, however after a certain point (40oC), the enzymes were becoming denatured and this caused them to become useless which is why the reaction slowed to a halt after this temperature. This was a poor experiment because: The potato chips were very hard to get exactly the same. This inaccuracy caused the surface area to differ between chips, which means that a small linear error will make a big surface area error. To counter this, a machine should be used to cut the chips to a preset size and would be very accurate. Measuring effervescence was very inaccurate. The Bubbles tended to burst when they were made which caused the overall amount of bubbles to be inaccurate. To prevent this, a syringe could be used or the gas bubbled up through water to get an accurate measure of the amount produced. The temperature of the potato chip when it was placed into the substrate, this means that the enzymes may still be working while they are being heated to the desired temperature, so if the temperature was 80oC then the enzyme may work hard for the first minute or so because the potato is still heating up when in fact 80oC should cause the enzyme activity to become nil. This probably accounted for some anomalies we received after doing this experiment. In order to counter this, the potato should be placed into a water bath matching the temperature of the substrate; this would ensure that the chip was already denatured if it would be so and also that an accurate reading was obtained from the very beginning. Also worth noting in relevance to the pre-mentioned error is the fact that the chip would float under high temperatures which means that the surface area would not be equal all the way through the experiment. A small surface area error would probably lead to a large rate of reaction mis-calculation. The reaction itself caused heat because it is an exothermic reaction which could alter the rate of reaction in itself. During the reaction substrate was used up which caused the reaction to slow to a halt after a while despite the fact that the enzymes were still functional, more substrate than was needed would have countered this and given true readings. Perhaps the most serious error in the whole experiment though was the fact that the gas expanded as the temperatures rose which would throw the results off completely. In order to counter this, the gas would need to be collected and cooled to room temperature in order to get perfectly accurately results.

Effect of Temperature on Rate of Reaction of Catalase 8.7 of 10 on the basis of 3750 Review.