Question

Lab Time Answer the Following Questions Evolution ofbubbles is usually observed when pouring H;O2 on an open wound, but not found when H2O is poured on the surface of unbroken skin. Why is this? Explain the reason for the bubbling by use of a chemical reaction. 1. 2. Estimate the optimum temperature for the catalase catalyzed reaction. What would you expect if the experiment is carried out with catalase at 50 degrees? Explain at the molecular level what change is taking place in the enzyme. 3. What would you expect if the experiment is carried out with hydrogen peroxide at 50 degrees? Explain at the molecular level what change is taking place in the substrate. 4. 130

Answer 1

1. When hydrogen peroxide comes in contact with the wound, the evolution of bubbles is because it comes into contact with an enzyme called catalase. Human body cells consist of catalase, so at the wound or injury region the tissue are damaged resulting the release of the catalase enzyme which react with the peroxide. Therefore you can see the bubbles when you pour hydrogen peroxide on a cut skin, these bubbles are of oxygen gas. Where as on the unbroken skin, the catalase enzyme is not released and do not available to react with hydrogen peroxide.

The chemical reaction is catalysed by the enzyme called catalase leading to the decomposition of hydrogen peroxide into water and oxygen gas evolution as shown below.

Catalase

2H₂O₂$\rightarrow$ 2H₂O +O₂ gas

2. The optimum temperature for the catalase catalysed reaction is 37 ⁰C. As it is the human body temperature at which the catalase function at its best.

3. If you carry out the experiment at 50⁰ C temperature of catalase enzyme reaction. It causes the reduction in catalytic activity of catalase enzyme and results into the complete loss of the reactivity of catalase enzyme at 50 ⁰C. At the end the enzyme catalase denatures and its structure get disrupted. Beyond the optimum temperature the activity of the enzyme decreases.

4. Hydrogen peroxide (H₂O₂) is an important regulator of cellular events leading to glucose transport activation in mammalian skeletal muscle. The substrate for catalase is hydrogen peroxide and the products of its decomposition are water and oxygen. It is similar to most chemical reactions, the rate of an enzyme-catalyzed reaction increases as the temperature is raised. A ten degree centigrade rise in temperature will increase the activity of most enzymes by 50 to 100%.

The thermal decomposition of hydrogen peroxide is observed at its boiling point that means 150⁰C