The effect of temperature on the activity of Trypsin.

The effect of temperature on the activity of Trypsin.

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The effect of temperature on the activity of Trypsin.

Aim: Investigate the activity of Trypsin at different temperatures.

Hypothesis:

Introduction: Casein is protein present cow milk, when mixed with water it is a cloudy liquid until all the suspension dissolves this action is catalysed by the action of the enzyme Trypsin. Trypsin as a protein is effected by temperature; I’ll be investigating this effect in this experiment. At high temperatures enzymes become denatured, this means that the active site becomes permanently changed, and the substrate molecule can no longer bind to it therefore the enzyme stops working, and the reaction isn’t catalysed. There are two ideas explaining how enzymes work, which are the lock and key hypothesis and the induced fit hypothesis. In both hypothesis’ the substrate and the enzyme fit into each other where the catalysed process occurs, the difference being that with the lock and key hypothesis the substrate molecule already is shaped to fit in the binding site of the enzyme where as in the induced fit hypothesis the binding site of the enzymes changes shape to fit the substrate.

Prediction: I will be using three temperature to see there effect on the enzyme; room temperature(25°C), 40-45°C, 80-85°C. I predict that the enzyme will act fastest in the 40-45°C range as this is close the temperature found in animals where this enzyme is found.

Equipment: Casein suspension Trypsin solution, 0.5% Distilled water. Test tubes and rack Graduated pipettes or syringes Water baths ( or Glass beakers) Thermometer Black card Stopwatch.

Method: 1.Set up water bath at 40°C. 2.Pipette 5cm³ of casein suspension in to one test tube and the same quantity of Trypsin solution into another test tube. 3.Stand both test tubes in the water bath and leave them for several minutes to reach the temperature of the water bath (3 minutes will do). 4.Meanwhile, set up a control 5 cm³ of casein suspension with the same quantity of distilled water. Stand this tube in the water bath. 5.Mix the enzyme and the substrate together and rplace the tube in the water bath. Start a stop watch immmediatley. 6.Observe the contenst of the tube carefully, checking the visibitly against a balck card, and record the time taken for the suspension to become clear. 7.Repeat this procedure at the set temperatures; do not use a water bath for the room temperature test. Use the same volumes of casein suspension and enzyme solutions each time.

Results:

Temperature(°C) Time (Seconds) Observed changes 25 600 Beginning to clear. 40-45 350 Cleared at top. 80-85 600 Nothing happened.

Discussion: These results quite clearly show the enzyme worked best in the 40-45°C range, this is to be expected at enzymes are found mainly in animals whose body temperature is about 40°C(~38°Cat the core). The 80°C the enzyme showed no effect this is because at these temperature proteins’ tertiary structure changes, this is what causes the denaturing of enzymes. Using the current accepted idea as to how enzymes work I believe that once it’s denatured the substrate no longer fit the binding site meaning the enzyme no longer works. At room temperature the enzyme worked but at a much slower rate, by the end of the experiment the solution had only become slightly clearer than the control.

Conclusion: The optimum temperature for typsin is around 40°C which is roughly body temperature. This is useful as all reaction in living things would happen far too slowly for metabolic processes to take place at a reasonable rate without enzymes. Low temperatures slow the activity of enzymes like Trypsin while high ones stop them forever, by permanently damaging the structure. I predicted this in my prediction where I explained the process by which we believe how enzymes work, the lock and key hypothesis and the induced fit hypothesis, both account for how high temperatures damages enzymes and denatures them.

Evaluation: This experiment has a few flaws in the fact that it’s not quantative; also, it leaves it down to the eye to accurately asses’ clarity of the solution which is not very practical. A better idea would be to use a light meter to calculate the amount of light that has passed through the solution. This would be able to give a more mutative evaluation of the results and therefore a better idea of the effects of temperature eon Trypsin enzyme activity.