What is the Catalase Enzyme?
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
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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.
FAQs on Catalase Enzyme
1. What is the catalase enzyme and where is it found?
Catalase is a common enzyme found in nearly all living organisms exposed to oxygen, including humans, plants, and microbes. It is an antioxidant enzyme that plays a crucial role in protecting cells from damage. It is particularly abundant in organelles like peroxisomes and in organs such as the liver.
2. What is the main function of catalase in living cells?
The primary function of catalase is to protect cells from oxidative stress. It does this by catalysing the decomposition of hydrogen peroxide (H₂O₂), a harmful byproduct of metabolic processes, into harmless water (H₂O) and oxygen (O₂). This prevents the build-up of toxic substances that could otherwise damage cellular components like DNA and proteins.
3. What is the chemical reaction that catalase speeds up?
Catalase dramatically accelerates the breakdown of hydrogen peroxide. The overall chemical reaction it catalyses is: 2H₂O₂ → 2H₂O + O₂. This reaction is extremely rapid, with a single catalase molecule capable of converting millions of hydrogen peroxide molecules into water and oxygen every second.
4. How do factors like temperature and pH affect the activity of catalase?
Like most enzymes, catalase activity is highly dependent on environmental conditions. It has an optimal pH and temperature range where it functions most efficiently. For human catalase, the optimal pH is around 7 (neutral). Extreme pH levels or very high temperatures can cause the enzyme to denature, altering its three-dimensional shape and destroying its catalytic activity.
5. What is the structure of a catalase enzyme molecule?
Catalase is a complex protein. It has a tetrameric structure, meaning it is composed of four identical polypeptide chains (subunits). Each of these four subunits contains a crucial heme group with an iron atom at its centre. This heme group is essential for the enzyme's ability to react with and break down hydrogen peroxide.
6. Why is the liver particularly rich in catalase?
The liver is the body's primary site for detoxification. Many metabolic processes that occur in the liver produce harmful byproducts, including large amounts of hydrogen peroxide. The high concentration of catalase in the liver is a protective mechanism that allows it to efficiently neutralise this toxic compound, preventing damage to liver cells.
7. What are some important industrial applications of catalase?
Due to its efficiency in breaking down hydrogen peroxide, catalase has several industrial uses. These include:
- In the food industry, to remove hydrogen peroxide from milk before making cheese.
- In the textile industry, to remove residual hydrogen peroxide from fabrics after bleaching.
- As a disinfecting agent in some contact lens cleaning solutions.
- In food packaging to prevent the oxidation of food products.
8. How is a lack of catalase linked to the greying of hair?
Hair gets its colour from the pigment melanin. The production of melanin can be disrupted by hydrogen peroxide. As we age, the levels of catalase in our hair follicles can decrease. This leads to a build-up of hydrogen peroxide, which bleaches the hair shaft from the inside out, contributing to the greying process.
9. What happens to the body if there is a catalase deficiency?
A deficiency in catalase can lead to a condition known as acatalasemia. In individuals with this condition, the body's ability to break down hydrogen peroxide is impaired. This increases the risk of cellular damage from oxidative stress, which can lead to complications such as oral ulcers and an increased risk for certain chronic conditions.
10. Which common foods are good sources of catalase?
Many fresh fruits and vegetables are rich in the catalase enzyme. Some of the best food sources include:
- Sprouts (like wheatgrass and broccoli sprouts)
- Onions and garlic
- Broccoli, celery, and cabbage
- Potatoes and sweet potatoes
- Fruits like avocado, pineapple, and kiwi
