Catalase is a globular protein and a heme-containing enzyme. A globular protein regulates the rate of reaction by its presence as a catalyst. It contains an active site allowing substrates with a complementary shape identical to the active site to bind to it. An enzyme-substrate complex is produced after the substrate binds to the active site. The enzyme-substrate complex creates an alternative pathway that reduces activation energy for the reaction. In the case of catalase reacting with hydrogen peroxide, hydrogen peroxide molecules bind to catalase active sites, it then interacts with the iron atom from the heme group, which triggers the hydrogen peroxide to be broken down to oxygen and water.
Catalase can be found in most living organisms, it acts as an antioxidant enzyme that breaks down cellular hydrogen peroxide. Catalase is found mostly in the liver in the human body. Catalase is important in living cells as it reduces oxidative stress. Oxidative stress is defined as the imbalance of the amount of free radicals and antioxidants in the body. (Dix M, 2018) Catalase reduces oxidative stress by balancing reactive oxygen species [ROS] in cell tissues. Oxidative stress may lead to tissue injury, where an accumulation of ROS may lead to an imbalance of oxidative stress that damages biomacromolecules, including DNA which may result in apoptosis and oncosis. (Authen, R.L. & Davis J.M, 2009) Oxidative stress increases aging, the risk of diabetes, cancer and neuronal damage. This may over-activate the TRPV4 protein channel, leading to heightened rates of renal dysfunction and tissue damage. (Hong. Z. et al, 2016) Hydrogen peroxide is a cellular ROS produced naturally in the body as a byproduct of cellular respiration. Catalase breaks down hydrogen peroxide (2H2O2 → 2H2O+O2) into oxygen and water reducing the accumulation of hydrogen peroxide in cells. Hydrogen peroxide is a ROS that may cause oxidative damage towards cellular components. (Ransy. C. et al, 2020) Therefore, catalase is crucial in the role of reducing oxidative stress in the body.
Ethanol is the most common form of alcohol found in alcoholic beverages. Different alcohols have different concentrations of ethanol, usually, people consume ranges from 1% to 40% in the form of beer, wine, liquor and spirits. (Yerby. N, 2023).The breakdown of alcohol after consumption occurs in the liver, where catalase levels are the highest. Catalase is located in peroxisomes that undergo oxidative reactions using the molecular oxygen obtained after breaking down cellular hydrogen peroxide. Ethanol is metabolized by catalase to form acetaldehyde, then acetaldehyde turns into acetate by mechanisms of aldehyde dehydrogenase; ethanol metabolism also creates ROS as byproducts. Therefore ethanol in the process of catalase breaking down hydrogen peroxide becomes a competitive inhibitor by occupying catalase active sites. (Biomolecule-Enzymes, n.d.) This prevents the hydrogen peroxide molecule from binding to catalytic sites and therefore can’t be broken down. Chronic alcohol consumption may lead to sustained levels of catalase inhibition, and increased levels of ROS contributing to oxidative stress may cause feedback inhibition where the synthesis of signaling pathways can cause the inhibition or suppressed expression of the enzyme catalase. (Choi et al., 2009) The observation of ethanol inhibition may be shown through the volume of oxygen gas produced from the breakdown of hydrogen peroxide
