EXPERIMENT 10.2 Objective. To study the effect of temperature on the activity of salivary amylase on starch.

 

                           EXPERIMENT 10.2

Objective. To study the effect of temperature on the activity of salivary amylase on starch.

REQUIREMENTS

Test tubes, test tube stands, pipettes, beakers, cotton, funnel, water bath, spirit lamp or burner, measuring cylinder, starch, sodium chloride, distilled water, iodine solution, iodide, etc.

PREPARATIONS

1. 1% Starch solution. To 10 ml of distilled water add 1 g of soluble starch to make it into a thick paste. Boil 90 ml of distilled water and to it add 10 ml of the starch paste already prepared, gradually by stirring. Leave the solution overnight and then filter to get 1% starch solution.

2.1% NaCl solution. Dissolve 1 g NaCl in 100 ml of distilled water.

3.Collection of saliva. Make a thin film of cotton and dip it into water. Drain off the water of the cotton and spread it over the mouth of funnel in such a way that it acts as filter. Keep the funnel over a clean test tube.Now chew a piece of rubber and pour the incoming saliva into the funnel. Filtered saliva will collect in the test tube. Take 1 ml of saliva and add 19 ml of water to get 1: 20 dilution of the enzyme.

PROCEDURE

1. Make three series of test tubes having 1 ml of iodine solution in each. Keep them separately in three stands.

2. Make three experimental test tubes each having 5 ml of 1% starch and 1 ml of 1% NaCl solution. Maintain them at three different temperature viz. 5±2°C, 37 ± 2°C and 70 ± 2°C in different water baths. (To maintain low temperature of 5°C, make use of ice).

3.Add 1 ml of diluted enzyme in all the three experimental tubes. With the help of dropper, take a drop from these test tubes and add to the tube containing iodine. Not the time of adding as zero minute.

4.After an interval of 1 minutes again take a drop from each tube and pour it to the iodine tubes, and note the change in colour of iodine. Keep on repeating the experiment at an interval of every 2 minutes till the colour of iodine does not change.

Note the time taken for by different experimental tubes till they do not give any colour with iodine.

OBSERVATION

RESULT

It takes less time to reach achromic point at 37°C as the enzyme is maximum active at this temperature, while at higher and lower temperatures more time is taken to reach the achromic point.

EXPLANATION

All enzymes are proteinaceous in nature. At lower temperature, the enzyme (salivary amylase) is deactivated and at higher temperature, the enzyme is denatured. Therefore, more time will be taken by the enzyme to digest the starch at lower and higher temperatures. At 37°C, the enzyme is most active, hence, takes less time to digest the starch.