مقاله انگلیسی رایگان در مورد آنزیم کاتالاز: بهبود زیست شناسی و صنایع غذایی – الزویر 2018

The enzyme catalase is known to catalyse the breakdown of hydrogen peroxide into oxygen and water. Hydrogen peroxide metabolism is mainly regulated by this enzyme. Catalase is a common enzyme found in nearly all living organisms. It has one of the highest turnovers of all enzymes as it has the capacity to decompose more than one million molecules of hydrogen peroxide, per molecule of enzyme. Catalase has been used as an important enzyme in many biotechnological areas including bioremediation. This paper gives a review of its use and application in the field of bioremediation as an indicator of hydrocarbon degradation in soil (an important aspect in bioremediation of crude oil pollution), as a provider of oxygen in aerobic bioremediation process and in the removal of H2O2 from bleaching industry effluent and also its potential use in the food industry.

Introduction

Catalase (EC 1.11.1.6) enzyme is an oxidoreductase enzyme as it plays a crucial role in quenching the reactive oxygen species (ROS), i.e. hydrogen peroxide, often produced as a by-product of aerobic respiration (Beers and Sizer., 1952). Hence it acts as an antioxidant and protects the cell against oxidative stress (Abbott et al., 2009, Kirkman et al., 1987). The enzyme is found in a wide range of aerobic and anaerobic organisms. Catalase has one of the highest turnover number as one molecule of enzyme hydrolysing over a million molecules of the substrate i.e. hydrogen peroxide per second. New applications for catalases are constantly emerging thanks to their high turnover number (Lončar and Fraaije 2015, Zamocky et al., 1999), distinct evolutionary origin, reasonably simple (Alptekin et al. 2008) and well-defined reaction mechanisms (Baeza et al., 2013). The basic mechanism of the working of this enzyme involves the breakdown and subsequent breakdown of the reactive oxygen specie i.e. hydrogen peroxide (H2O2) into oxygen and water thus relieving the oxidative stress caused by this substrate as depicted in the following reaction (Barynin et al., 2001). Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long. It contains four porphyrin heme (iron) groups that allow the enzyme to react with the hydrogen peroxide. Catalase has a fairly broad range of working from 4-11 optimum pH (Beers, 1961; Calera et al., 2000; Correia et al., 1994; Diaz et al., 2012). Catalase is usually located in a cellular, bipolar environment organelle called the peroxisome (Fita et al., 1985). As this enzyme is found in mainly all organisms (aerobic and anaerobic), it has been exploited in many applications including food processing, textile, paper, pharmaceutical industry and also in the field of bioremediation as one of the upcoming areas of its application (Gromada et al., 1997; Hussein 2012; . Beers et al., 1952; Youn et al 1995).This paper intends to give an account of how this enzyme has been exploited in the process of bioremediation in order to clean the environment of unwanted substances.