FST Lab 12 (demonstrate the effect of temperature on enzyme-catalyzed reactions and To observe the catalytic action of “catalase” on hydrogen peroxide)

 LAB- 12

OBJECTIVE:

• To demonstrate the effect of temperature on enzyme-catalyzed reactions. 

• To observe the catalytic action of “catalase” on hydrogen peroxide.

REAGENTS: 

• 3% hydrogen peroxide 

• Any living tissue containing catalase (such as liver cells or potatoes)

THEORY:

Biocatalyst: enzymes 

Enzymes are catalysts that speed up biochemical reactions in living organisms. As catalysts, enzymes are only required in very low concentrations, and they speed up reactions without themselves being consumed during the reaction. We usually describe enzymes as being capable of catalyzing the conversion of substrate molecules into product molecules as follows:

Effect of temperature on enzyme activity

The effects of temperature on enzyme activity are quite complex, and can be regarded as two forces acting simultaneously but in opposite directions. As the temperature is raised, the rate of molecular movement and hence the rate of reaction increases, but at the same time there is a progressive inactivation caused by denaturation of the enzyme protein. This becomes more pronounced as the temperature increases, so that an apparent temperature optimum (Topt) is observed.

Principle of catalase test:

The enzyme catalase is present in both animal and plant tissues where it can break down hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly oxidative molecule, meaning it causes processes similar to rusting. This is why anti-oxidants are important because they prevent tissues from oxidizing by getting rid of oxidizing molecules such as hydrogen peroxide.

PROCEDURE:

• Take 3 test tube

• Add chunks of potato in it

• Pour 5ml 3% H2O in this tube

• Observe the O2 bubbles and measure its height.

OBSERVATION:

TEST TUBE	CONTENT	TEMPERATURE°C	HEIGHT OF BUBBLES (cm)
1	Potato + hydrogen peroxide	25°C	0.9
2	Potato + hydrogen peroxide	100°C	0
3	Potato + hydrogen peroxide	4°C	0.7

RESULT: The height of bubbles at 25°C, 100°C and 4°C is 0.9, 0 and 0.7 respectively.

DISCUSSION:

Our experiment aims to demonstrate the effect of temperature on an enzyme-catalyzed reaction and to observe the catalytic action of catalase on hydrogen peroxide. We placed three chunks of potato in three different test tubes, each containing 5 ml of hydrogen peroxide. The test tubes were maintained at temperatures of 25°C, 100°C, and 4°C, respectively. According to our observations, bubbles formed to a height of 0.9 cm in the first test tube and 0.7 cm in the third test tube. In the second test tube, no bubbles appeared at all, as the enzymes denatured at the high boiling point.