Thermotolerant and thermostable laccases

Abstract

Laccases are phenol-oxidizing, usually four-copper containing metalloenzymes. For industrial and biotechnological purposes, laccases were among the first fungal oxidoreductases providing larger-scale applications such as removal of polyphenols in wine and beverages, conversion of toxic compounds and textile dyes in waste waters, and in bleaching and removal of lignin from wood and non-wood fibres. In order to facilitate novel and more efficient bio-catalytic process applications, there is a need for laccases with improved biochemical properties, such as thermostability and thermotolerance. This review gives a current overview on the sources and characteristics of such laccases, with particular emphasis on the fungal enzymes.

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

“…The role of lignin-degrading enzymes in the treatment of contaminated effluent is also established, however their utilization demands a thorough understanding of lignin degrading organisms and their enzyme systems. Although oxidative enzymes produced by fungi are also used for the degradation of azo dyes, bacterial enzymes generally have greater heat stability and broader substrate specificity (Hilden et al, 2009;Lee et al, 2003;Reiss et al, 2011). Moreover, these can be produced in a short time, operating in aqueous solvent at neutral to basic pH (Wells et al, 2006), which is a common pH of real dyecontaminated textile wastewater.…”

“…Our review of the literature suggests that there has not yet been serious work aimed at the treatment of azo dyes using immobilized azoreductases. Some researchers reported decolorization of azo dyes using immobilized or spore-bound bacterial laccases (Held et al, 2005;Hilden et al, 2009). The crude enzyme mixture containing hydrolase was selfsustaining and the respective reaction occurred without any necessary cofactors.…”

Mecanismos envolvidos na biodegradação de materiais lignocelulósicos e aplicações tecnológicas correlatas

“…88 Dentre as enzimas oxidativas, as lacases têm se aproximado rapidamente da aplicação comercial nos processos de biobranqueamento de pastas celulósicas, enquanto as MnPs ainda apresentam restrições devido à limitada capacidade de se produzir a enzima em escala comercial a preços baixos. 9,[89][90][91] O biobranqueamento com lacases está baseado na habilidade dessa enzima em oxidar alguns mediadores que, por sua vez, atuam como agentes oxidantes da lignina residual presente nas polpas celulósicas. A lignina oxidada é então removida por um processo de extração alcalina.…”

Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen

“…15 The plots of v 0 (initial rate) vs. pH (Figure 9 for complex 1, and S2 for complex 2) show sigmoid-shape profiles and reveal pK a values of 9…”

“…14 Considering the high academic and industrial interest on these enzyme systems, and that their use is sometimes limited mainly because of the optimal pH and temperature ranges, 15 model complexes are considered as an alternative. Because of this, several compounds have been synthesized, characterized and tested as catalysts for oxidative processes involving molecular oxygen and hydrogen peroxide.…”