An Experiment To Investigate The Effect Of Temperature on The Action Of The Enzyme Trypsin On Casein

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AN EXPERIMENT TO INVESTIGATE THE EFFECT OF TEMPERATURE ON THE ACTION OF THE ENZYME TRYPSIN ON CASEIN

APPARATUS

Casein suspension, 4 per cent;

Trypsin solution, 0.5 per cent;

Distilled water;

Test tubes and rack;

Water baths;

Graduated pipettes or syringes

Thermometers;

Black card;

Electronic timer;

Marker pen,

INTRODUCTION

Casein is a protein found in milk. When a suspension of casein is hydrolysed, the suspension starts cloudy but becomes clearer as the products dissolve. This hydrolysis is catalysed by proteolytic enzymes such as trypsin. The aim of this experiment is to investigate the effect of temperature on the activity of trypsin, using a suspension of casein as the substrate. Changes in the clarity of the casein suspension will be easier to see if the tubes are checked periodically by holding them against a piece of black card.

METHOD

Set up the water baths with thermometers and maintain one at room temperature, one at 25°C, 35°C, 45°C, and 55°C. The temperature is read on a temperature in the range of 0- 60°C, and readings taken to the nearest increment, i.e. 0.5 of a degree. All should be turned on and left for at least 20 minutes as to allow the temperatures of each bath to equilibrate.
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Pipette 5 cm3 of the Casein suspension into one test tube, label this Casein room temperature, and also pipette 5 cm3 of the Trypsin solution into another test tube and label this Trypsin room temperature. Now set up a control test tube containing 5 cm3 of the Casein suspension and 5 cm3 of distilled water; label this control room temperature.

Stand all three test tubes in the water bath at room temperature and leave for 8 minutes as to allow the contents of the test tubes to reach the temperature of the water.

After such time ...

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