Question

Procedure A: A piece of fresh liver and little bit of water was put inside of test tube. The test tube was put inside of boiling water for five minutes. Test tube was taken out from boiling water and drained out the water. 2 mL of hydrogen peroxide was put inside of the test tube and only little bubbles (enzyme activity ) were formed.

Q1. What was the purpose of the assay performed?

Q2. Did increasing the temperature (heating the test tube) have an effect on enzyme activity? Briefly explain why.

Procedure B: 2mL of hydrogen peroxide was added to test tube. A piece of liver soaking in base/ alkaline solution was also put inside of test tube. Slowly, there are bubbles forming in almost to the top.

Q3. Under what pH condition is catalase most active? least active? Explain your answer using data from this part of the experiment.

Answer 1

1. The assay as performed to deterine the effect of temperature on enzyme activity. Doing the same at different temperatures will help in determining the optimal temperature of the enzyme, catalase.

2.Yes, increasing the temperature led to a decrease in enzyme activity as very little bubbles were formed due to the evolution of oxygen from hydrogen peroxide. At high temperatures, the enzyme gets denatured. High temperature causes distortion or damage in the structure of the enzyme, especially changes in the active site prevent the binding of the substrate or the ability of the enzyme to form the transition state and hence the enzyme activity reduces drastically.

3.Since the bubble formation as high in alkaline conditions ,it indicates that the conversion of hydrogen peroxide to water and oxygen (appears as bubbles ) by catalase is high. So catalase is most active in the neutral to alkaline pH conditions (7-11) and it will be least active in acidic conditions.