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The aim of the experiment is to investigate the effect of temperature on the activity of trypsin, using a suspension of casein as the substrate.

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Introduction

Aim: The aim of the experiment is to investigate the effect of temperature on the activity of trypsin, using a suspension of casein as the substrate. Hypothesis: Enzymes are substances that act as catalysts, in other words they increase the rate of chemical reactions. In biological system, this reaction might occur very slowly, or not at all, in the absence of an enzyme. Enzymes will greatly increase the rate of formation of the product. Enzymes can increase the rate of reaction by a factor of at least one million. Most enzymes are large protein molecules, with complex three-dimensional shapes. This diagram shows the complex 3D-structure of trypsin. Trypsin is an enzyme that acts to degrade protein; it is often referred to as a proteolytic enzyme, or proteinase. Trypsin is one of the three principal digestive proteinases, the other two being pepsin and chymotrypsin . In the digestive process, trypsin acts with the other proteinases to break down dietary protein molecules to their component peptides and amino acids. Trypsin continues the process of digestion (begun in the stomach) in the small intestine where a slightly alkaline environment (about pH 8) promotes its maximal enzymatic activity. Trypsin, produced in an inactive form by the pancreas, is remarkably similar in chemical composition and in structure to the other chief pancreatic proteinase, chymotrypsin. ...read more.

Middle

Enzymes work best at around body temperature. This is how I expect the graphs to look during the experiment. Graph 1. Graph 2 Optimum Temp Rate of Reaction Time/ Min Temperature/ �C Temperature/�C The first experiment to take place was with two other enzymes and they were pepsin and protease. However, during the experiments, the pepsin and protease were working with the casein substrate at a very slow rate, so doing the experiment with the protease and pepsin would have been very time consuming. The point of doing trypsin, pepsin and protease was to make a comparisons about their optimum temperature. So I carried out the experiment just looking at the effect of temperature on the enzyme trypsin. I used trypsin at 0.5% molar concentration because if I were to anymore the reaction would go quick and if I was to add any less, it would be very slow. I also used to 4% molar concentration of casein because if I was to use too much, there would more interactions and therefore the experiment would finish quickly. If I used to little the amount of interactions would be slow so the experiment would be slow. Method: Apparatus: 1.Casein Suspension, 4% 2. Trypsin solution, 0.5% 3. Distilled water 4. ...read more.

Conclusion

The following are precautions taken whilst doing the experiments to decrease the level of inaccuracy: - The equipment was well washed so that any impurities could be washed off and therefore not contaminate the water and the solution, which may alter the optimum temperature of the enzyme and change my results. I did not hold the thermometer as I would conduct heat into the thermometer and alter the readings so therefore it was left to stand in the beaker. To get a more accurate set of results, using shorter temperature intervals would show me the optimum temperature more clearly. I was using 5 �C if was to use a 2 �C I think I would get a more accurate set of results. Also, the concentration of trypsin, if it was changed it could show the optimum temperature more accurately. The experiment, with an increased amount of trypsin concentration, would have gone faster. The following sources errors, in my opinion have affected my results, they are: - The rounding up of temperatures and measurements. A lot of the heat could have been conducted into the desk from the beaker, causing our temperature readings to fluctuate. Some of the heat could have been radiated away. Also some of the heat heated up the thermometer therefore maybe a digital thermometer could have been used or maybe a calorimeter to get an accurate reading of the temperature. Also some the heat may have been lost by convection currents. ...read more.

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