An Investigation Into a Reaction Catalysed by a Protease

An Investigation Into a Reaction Catalysed by a Protease
Aim. To investigate the effect of temperature and the effectiveness of this enzyme in breaking down the gelatine (protein) on the back of photographic film. Prediction I predict that the effect of the temperature will be that the higher the temperature the quicker the enzyme will break down the gelatine, but the temperature will have to be an optimum temperature because if it is too high, the enzyme will be denatured. If the temperature is too low, the enzyme will not work and stay stable. Increasing the temperature provides more heat energy. This increases the kinetic energy and makes the enzyme molecules move faster. There will be an increase in the number of collisions and this will increase the rates of reaction. If the temperature continues to increase beyond 40Â?c, the molecules move even faster, but the structure of the enzyme molecules has so much energy that the bonds break. The enzyme begins to lose its globular shape, which effects the active site, and the enzyme becomes denatured. Also, for every enzyme there is an optimum PH at which the reaction it catalyses proceeds most rapidly. Many enzymes work within a PH range of an about 5-9 and works most efficiently at neutral of PH 7, that is why I will be using water. Equipment *10 pieces of photographic film *20ml of protease enzyme in each test tube *Water baths (23Â?c, 40Â?c, 50Â?c, 60Â?c, and 70Â?c) *Buffer (5ml in each test tube) *Stop watch *Distilled water *10 boiling tubes *Goggles Safety Wear goggles, wear a lab coat, wash your hands after experiment, make sure cotton is thread through the photographic film to avoid contamination. Variables *Temperature is kept constant and controlled
The film size is the same throughout
*Range of temperatures is used *Use of a buffer (chemical to maintain a constant PH) Method Firstly set up the water baths at the specific temperatures and leave one at room temperature. Put 5ml of buffer into each boiling tube using a syringe, the buffer is used to maintain a constant PH. Then add 20ml of distilled water, this is used as a control for each temperature, so that it is to prove that it is the protease that breaks down the gelatine. Shake all the boiling tubes so that they are mixed. Then place the boiling tubes into each water bath, plus the control and leave for 5 minutes so that it reaches the appropriate temperature. Then add the photographic film (which is attached to cotton) and time it to see how long it takes for the photographic film to go transparent. Do this to all the temperatures. Results Results 1 temperature time IT took for the protease TO break down the silver nitrate time IT took for the control experiment 30�c 25.13 - 35�c 17.30 - 40�c 13.12 - 45�c 9.40 - 50�c 8.19 - Result 2 temperature time IT took for protease TO break down the silver nitrate time IT took for the control experiment 30�c 26.14 - 35�c 18.21 - 40�c 12.17 - 45�c 10.33 - 50�c 8.24 - � Temperature temperature average time IT took for the protease TO break down the silver nitrate 30�c 25.13 35�c 17.75 40�c 12.64 45�c 9.86 50�c 8.21 Conclusion I have noticed that my prediction is correct. The effect of temperature is that the higher the temperature the quicker the enzyme will break down the gelatine, and the photographic film turns transparent. As the graph shows, the higher the temperature the quicker the enzyme works at breaking down the gelatine. The higher the temperature, the ore kinetic energy is produced, and this makes the enzyme molecules and the substrate molecules move faster. There will be an increase in the number of collisions and this will increase the rate of reaction. If the temperature continues to increase beyond 40�c, the molecules move even faster but the structure of the enzyme has so much kinetic energy that bonds break. The enzyme begins to lose its globular shape, which effects the active site. The enzyme and the substrate molecules (protease and the gelatine), they combine to form an enzyme-substrate complex before the products of the reaction are released. This ?lock and key? theory increases the probability that they will react. The chances of molecular collision taking place are thus increased at higher temperatures so it is more likely that enzyme- substrate complex will be formed. If the temperature gets too high, the vibrations become too violent, chemical bonds in the enzyme break; therefore the enzymes become denatured. Also extremes of PH cause the bonds to break resulting in the enzyme becoming denatured. For every enzyme there is an optimum PH at which the reaction it catalyses proceeds most rapidly. Many enzymes work within a PH range of about 5-9 and works most efficiently at neutral of PH 7. As my graph shows the enzyme worked at the lowest temperature which was 30�c, but it took longer because the molecules hadn?t gained much kinetic energy, as the temperature wasn?t high enough, that is why it took about 25-26 minutes to become transparent. My graph does not show when the enzyme becomes denatured. I predict that it would become denatured around 70�c or 80�c. The majority of enzymes become denatured around 45�c. The enzyme (protease) worked faster around 50�c. it took less time for the photographic film to become transparent. Evaluation I have found that I would need a wider range of temperatures for observation, as the temperatures I used weren?t high enough to denature the enzymes, so I would need to use temperatures up to about 80�c for more accurate results. The size of the photographic film wasn?t exact; it was cut to an approximate size so it wasn?t exact. To make sure it was the exact measurements as all the rest I would need to use a template. The volumes were pretty accurate but they could of been more precise as I only used a syringe to measure the solution with, but if I used a volumetric pipette all my volumes would of been the precise measurement. There was about 8 test tubes in the water bath that I used, as other members in my class was using it so the temperature wasn?t kept totally constant. The temperature was also not kept constant when I kept taking the test tube out to check the ?clearing?, so the temperature was not maintained. To improve this I would need a deep enough water bath so that I could keep the test tube underwater whilst checking the ?clearing?. I also found that when I removed the photographic film for observation it was difficult to replace, to stop this from happening, I could use a beaker, so that it gives me more space to put the film back in. I also found that I might not of timed the correct time of clearing as I struggled to see the photographic film in the test tube. To prevent this I could use a beaker instead of a test tube so that I could monitor the photographic film at all times.

An Investigation Into a Reaction Catalysed by a Protease 7 of 10 on the basis of 777 Review.