دانلود رایگان مقاله لاتین کاتالیزور آنزیمی از سایت الزویر
عنوان فارسی مقاله:
توسعه کاتالیزورهای آنزیمی مستحکم برای رنگ زدایی رنگ
عنوان انگلیسی مقاله:
Development of strong enzymatic biocatalysts for dye decolorization
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Laccases (EC 1.10.3.2) are members of the multicopper oxidase family and are potential tools in a wide number of biotechnological processes mainly due to their high and nonspecific oxidation capacity, lack of cofactors, and the use of readily available oxygen as an electron acceptor (Claus, 2003). This enzyme is characterized by having four copper(II) ions per domain and catalyzes the fourelectron reduction of O2 to H2O coupled with the oxidation of phenolic compounds, diamines or aromatic amines (Thurston, 1994). Additionally, the reactivity of the enzyme can be enhanced by mediators such as 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonate) (ABTS), which modifies the reactivity towards other substrates that laccase alone cannot oxidize (Galli and Gentili, 2004). Laccase could be applied in many fields, such as delignification of lignocellulosic biomass, detoxification of recalcitrant pollutants, decolorization of industrial dyes and textile dye effluents, biological bleaching in pulp and paper industries, juice and wine clarification, and biosensors (Rodríguez Couto and Toca Herrera, 2006). Only a few bacterial laccases have been studied so far, although rapid progress in genome analysis suggests that these enzymes are widespread in bacteria (Sharma et al., 2007). Escherichia coli CueO is a 53.4-kDa periplasmic laccase involved in the Cu efflux system under aerobic conditions. CueO would be responsible for the oxidation of extremely toxic Cu(I) to less toxic Cu(II) in vivo (Rensing and Grass, 2003). Although the native function and in vivo substrate of CueO remain unclear, it is able to oxidize catechols (Kataoka et al., 2007), siderophores (Li et al., 2007) and recalcitrant molecules such as polycyclic aromatic hydrocarbons (PHA) (Zeng et al., 2011). The use of laccases for industrial bio-oxidations has emerged in recent years due to the advantage that these enzymes, in contrast with peroxidases, do not require hydrogen peroxide (Loera Corral Octavio et al., 2006). Furthermore, laccases accept a wide range of phenolic and non-phenolic compounds as substrates and produce water as the only by-product. This makes laccases suitable enzymes for a great number of green oxidation processes. The great potential and value in industrial and biotechnological applications have aroused a strong interest in obtaining a large amount of laccase for practical use. The stability and catalytic activity of free enzymes are dramatically decreased by process conditions, such as pH, temperature and ionic strength. The use of immobilized enzymes can overcome some of these limitations and provide stable catalysts with longer lifetimes (Singh et al., 2013). The purpose of the present study was the development of an effective method for the immobilization of Escherichia coli crude laccase and their use for bleaching of industrial dyes.
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کلمات کلیدی:
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