[Biology Class Notes] on Catalase Enzyme Pdf

It is an enzyme-containing heme group and known to catalyze the decomposition of hydrogen peroxide to water and oxygen. It is found in cells of almost all aerobic organisms. Peroxide is a byproduct continuously generated in the body from various metabolic reactions. However, the body must get rid of the peroxide generated because it is harmful to the body. Peroxide build-up and accumulation can turn toxic for cells and tissue in the body. So, enzyme catalase prevents the building up of peroxide in the organelles, cells, and tissues and safeguards them.

Catalase is commonly found in mammalian liver. It functions to prevent the cells from oxidative damage by reactive oxygen species or ROS. All living organisms exposed to oxygen have catalase enzymes to prevent the cell damage. The catalysis brought by catalase is energy efficient and helps the cells deal with environmental stress. The rate of catalysis is also very high for the catalase enzyme. For example- it can catalyze millions of hydrogen peroxide to form oxygen and water per second.

Chemical Nature of Catalase Enzyme

Catalase is a tetrameric enzyme containing four polypeptide chains with more than 500 amino acids each. It also contains a heme group with 4 iron molecules. Heme group allows the catalase to react with peroxide in the first place. Human catalase is stable at a pH level 7. For other catalases, the optimum pH range is between 4 to 11 depending upon the species. The temperature parameter for catalase to be the same is also similar.

The Catalase enzyme is also present in some anaerobic microorganisms and some fungi. While it is universally present in plants.

Functions of Catalase Enzyme

By the process of oxidation, a living body continuously generates free radicals. Free radicals are unstable molecules which also tend to cause instability to other molecules in the body. This leads to cell damage and onset of other malfunctions. It may also result in permanent cell or tissue damage giving rise to heart disease, infections, immunity suppression, etc. To combat all of these, catalase plays a vital role by dealing with the free radicals generated in the body.

In the first phase, catalase converts harmful free radicals into less harmful hydrogen peroxide and then catalyzes the conversion of hydrogen peroxide into water and oxygen. Because of its effective catalytic property catalase is also used as a therapeutic agent in oxidative stress-related diseases. It also has industrial applications and is used in food industries.

Catalase Enzyme Reaction

  Catalase

[2H_{2}O_{2} rightarrow H_{2}O + O_{2}]

The activity of catalase can be illustrated by taking a microbial sample and adding hydrogen peroxide to it. Bubble formation in the reaction indicates the release of oxygen. The activity of the enzyme is so rapid that it can be observed with naked eyes. This is because catalase has a higher rate of activity that generates a quick response. Besides, another by-product is gas which also releases in the reaction making the reaction easy to detect.