Oxidative biodegradation of phosphorothiolates by fungal laccase

Amitai, Gabriel; Adani, R.; Sod‐Moriah, Gali; Rabinovitz, I.; Vincze, A.; Leader, Haim; Chefetz, Benny; Leibovitz-Persky, Limor; Friesem, Dana; Hadar, Yitzhak

doi:10.1016/s0014-5793(98)01300-3

Cited by 117 publications

(51 citation statements)

References 22 publications

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“…132 O sistema lacase-mediador tem sido utilizado na deslignificação de polpas, [139][140][141][142][143] na degradação de corantes têxteis, 144,145 de hidrocarbonetos aromáticos, 146 de pesticidas e inseticidas, 147,148 e em síntese orgânica. 149,150 Na indústria de polpa e papel, as tecnológicas de branqueamento enzimático apresentam grandes vantagens pela substituição das etapas de branqueamento com cloro.…”

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Relevância de compostos de baixa massa molar produzidos por fungos e envolvidos na biodegradação da madeira

Arantes¹,

Milagres²

2009

Quím. Nova

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Recebido em 16/7/08; aceito em 27/1/09; publicado na web em 3/7/09 RELEVANCE OF LOW MOLECULAR WEIGHT COMPOUNDS PRODUCED BY FUNGI AND INVOLVED IN WOOD BIODEGRADATION. Over the last decade, evidences have been shown that the wood biodegradation by fungi is not only a result of the action of their enzymatic machinery but also of various low molecular weight non-enzymatic compounds, especially in fungi that promote brown and white decay, which in nature are the major wood decaying microorganisms. The present review focuses on the recent theories involving these low molecular weight compounds that act direct or synergistically with lignocellulolytic enzymes to attack the wood main macromolecular constituents, their relevance as potential degradative systems, in the overall wood biodegradation, and also outlines their potential biotechnological applications.Keywords: wood biodegradation; enzymes; low molecular weight compounds.A biodegradação de materiais lignocelulósicos, como a madeira, é um processo natural de reciclagem de matéria orgânica e o entendimento deste processo contribui com a compreensão do ciclo natural do carbono, que tem início na biossíntese dos seus constituintes a partir de H 2 O, CO 2 e energia solar e termina com a mineralização destes constituintes e liberação de CO 2 e H 2 O, em decorrência da decomposição causada principalmente por fungos.Por muito tempo o processo de biodegradação foi foco de muitos estudos devido à grande quantidade de madeira e produtos à base de madeira, que são danificados por ação de fungos, e devido à necessidade do desenvolvimento de métodos de prevenção à biodegradação menos ofensivos ao meio ambiente. Atualmente, os fungos degradadores de madeira e/ou seus sistemas degradativos têm sido intensivamente estudados em razão do elevado potencial de utilização em aplicações biotecnológicas, como na biodegradação de compostos xenobióticos, 1-3 biorremediação de solos, 1,4,5 biopolpação da madeira 6,7 e biobranqueamento de polpas celulósicas. [8][9][10] Uma vez que o desenvolvimento e a eficácia destes métodos/processos dependem principalmente do conhecimento dos mecanismos químicos e bioquímicos envolvidos na biodegradação dos constituintes da madeira, o entendimento destes mecanismos certamente irá contribuir para o desenvolvimento de novas aplicações, assim como para a melhoria das já existentes.Apesar do considerável conhecimento adquirido nas últimas dé-cadas a respeito da enzimologia da biodegradação dos constituintes da madeira, até os dias de hoje não se conhecem os mecanismos químicos e bioquímicos exatos empregados pelos fungos durante este processo. Contudo, sabe-se que o processo de biodegradação da madeira por fungos não pode ser explicado unicamente com base na ação das diversas enzimas lignocelulolíticas por eles secretadas. Dentro dessa abordagem, pesquisas recentes têm indicado uma participação expressiva de compostos de baixa massa molar (CBMM). 11,12Neste sentido, esta revisão tem como objetivo principal agrupar as diferentes teorias envolvendo CBMM produ...

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unclassified

Relevância de compostos de baixa massa molar produzidos por fungos e envolvidos na biodegradação da madeira

Arantes¹,

Milagres²

2009

Quím. Nova

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“…Based on product structure analysis, it has been proposed that laccase-oxidized ABTS can abstract an H atom from the lignin model compounds, leading to indirect laccase catalysis upon the oxidation of the compounds (25). To date, other types of mediators, particularly phenoxazines and N-OH compounds, also have been recognized for their mediation function in laccase catalysis (1, 6,17,29).Mediated laccase catalysis has been applied to a wide range of applications, such as pulp delignification (9, 10, 12, 22, 32), textile dye bleaching (31), polycyclic aromatic hydrocarbon degradation (16, 23), pesticide or insecticide degradation (1, 29), and organic synthesis (13,28). For the paper and pulp industry, novel biological or enzymatic bleaching technologies (including mediated laccase catalysis) have attracted increasing attention (9,10,12,14,22,27,32) because of concerns regarding the environmental impact of the chlorine-based oxidants currently being used in delignification or bleaching.…”

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confidence: 99%

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Redox Chemistry in Laccase-Catalyzed Oxidation of N-Hydroxy Compounds

Kulys

Duke

et al. 2000

Appl Environ Microbiol

271

165

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1-Hydroxybenzotriazole, violuric acid, and N-hydroxyacetanilide are three N-OH compounds capable of mediating a range of laccase-catalyzed biotransformations, such as paper pulp delignification and degradation of polycyclic hydrocarbons. The mechanism of their enzymatic oxidation was studied with seven fungal laccases. The oxidation had a bell-shaped pH-activity profile with an optimal pH ranging from 4 to 7. The oxidation rate was found to be dependent on the redox potential difference between the N-OH substrate and laccase. A laccase with a higher redox potential or an N-OH compound with a lower redox potential tended to have a higher oxidation rate. Similar to the enzymatic oxidation of phenols, phenoxazines, phenothiazines, and other redox-active compounds, an "outer-sphere" type of single-electron transfer from the substrate to laccase and proton release are speculated to be involved in the rate-limiting step for N-OH oxidation.Laccases (EC 1.10.3.2) are multi-Cu oxidases that can catalyze the oxidation of a range of reducing substances with the concomitant reduction of O 2 (for recent reviews, see reference 24 and references therein). Because of their capability of catalyzing the oxidation of aromatic compounds, laccases are receiving increasing attention as potential industrial enzymes in various applications, such as pulp delignification, wood fiber modification, dye or stain bleaching, chemical or medicinal synthesis, and contaminated water or soil remediation (15, 37).Laccases contain one type 1 (T1) Cu center, one type 2 (T2) Cu center, and one type 3 (T3) Cu center. The T2 and T3 sites form a trinuclear Cu cluster onto which O 2 is reduced. The T1 Cu oxidizes the reducing substrate and transfers electrons to the T2 and T3 Cu. Laccase is able to oxidize certain phenols with E 0 values higher than its own (0.5 to 0.8 V versus the normal hydrogen electrode [NHE]) (36). However, many inorganic and organic compounds with comparable E 0 values (such as 1,2,3,5-tetramethoxybenzene [18]) are not laccase substrates due to unfavorable kinetics. Under certain conditions, however, these compounds can be indirectly oxidized by laccase through the mediation of small, redox-active laccase substrates. 2,2Ј-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was the first compound found capable of efficiently mediating the laccase oxidation of high-E 0 , nonsubstrate lignin model compounds (such as veratryl alcohol and nonphenolic lignin model dimers) (8). Based on product structure analysis, it has been proposed that laccase-oxidized ABTS can abstract an H atom from the lignin model compounds, leading to indirect laccase catalysis upon the oxidation of the compounds (25). To date, other types of mediators, particularly phenoxazines and N-OH compounds, also have been recognized for their mediation function in laccase catalysis (1, 6,17,29).Mediated laccase catalysis has been applied to a wide range of applications, such as pulp delignification (9, 10, 12, 22, 32), textile dye bleaching (31), polycyclic aromatic h...

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“…This property can be accelerated by applying genetic engineering techniques. The unique Singh and Walker, 2006;Serdar et al, 1982.Somara andSiddavattam, 1995;Horne et al, 2002;Cheng et al, 1996;Cheng et al, 1997;Zhongli et al, 2001;Zhang et al, 2005;Chen and Mulchandani (1998);Chen et al, 1999;Amitai et al, 1998;Liu et al, 2001;Liu et al, 2004;Liu et al, 2001 Agrobacterium radiobacter Alteromonas sp. …”

Section: Role Of Catabolic Genes and Genetic Engineering For Pesticidmentioning

confidence: 99%