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Karlerik Eriksson - One of the best experts on this subject based on the ideXlab platform.
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comparison of fungal Laccases and redox mediators in oxidation of a nonphenolic lignin model compound
Applied and Environmental Microbiology, 1999Co-Authors: Karlerik ErikssonAbstract:Conventional pulp-bleaching techniques with chlorine or chlorine-based chemicals can, under certain conditions, generate chlorinated organic compounds that are toxic to the environment. The pulp and paper industry is facing an increasing pressure from environmentally concerned organizations to replace the conventional bleaching techniques with environmentally benign ones. Enzymatic bleaching methods have recently drawn much attention as being environmentally friendly. In addition to xylanase, Laccase has been the most actively investigated enzyme for biobleaching of kraft pulp because Laccase can be produced in large amounts at a reasonable price and use cheap oxygen as an electron acceptor. However, expensive redox mediators are still a hurdle in the implementation of Laccase in pulp bleaching. Laccase (EC 1.10.3.1) belongs to a family of multi-copper oxidases that are widespread in numerous fungi, in various plant species (18), in the bacterium Azospirillum lipoferum (10), and in a dozen of studied insects (25). Laccase has various functions, including participation in lignin biosynthesis (21), plant pathogenicity (22), the degradation of plant cell walls (12, 17), insect sclerotization (3), bacterial melanization (10), and melanin-related virulence for humans (26). Chemically, all of these functions of Laccases are related to oxidation of a range of aromatic substances. However, the net effect of such oxidations could be very different and even work in opposite directions. Plant Laccases, for example, oxidize monolignols to form polymeric lignins, whereas Laccases from white-rot fungi degrade and depolymerize lignins. In the degradation of lignin by white-rot fungi, the redox potential of the lignin-degrading enzymes has long been believed to play a crucial role because nonphenolic subunits, the most predominant lignin substructures in wood, have high redox potentials. The well-studied lignin peroxidase is able to oxidize nonphenolic aromatic compounds with very high ionization potentials such as 1,2-dimethoxybenzene (E1/2 = 1,500 mV) and veratryl alcohol (14, 20). Lignin peroxidase was thus once believed to be a key enzyme for fungal degradation of lignin, whereas Laccase was believed to be less important because it could not oxidize veratryl alcohol (a typical model compound for nonphenolic lignin). The highest redox potential of a Laccase reported so far does not exceed 800 mV, which is believed not to be high enough to oxidize a nonphenolic lignin structure. However, it has been demonstrated that Laccase is able to oxidize some compounds (redox mediators) with a higher redox potential than Laccase itself, although the mechanism by which this happens is not known (2, 7). In the presence of such redox mediators, Laccase is also able to oxidize nonphenolic lignin model compounds and decrease pulp kappa number to a great extent (5, 8). Several effective redox mediators have been reported so far (2, 5, 6, 8, 13). The importance of the redox potential of Laccases in the oxidation of lignin model compounds by Laccase/mediator systems will be addressed here. While much effort has been devoted to search for more effective redox mediators, the Laccase parameters governing lignin degradation and pulp bleaching are still not fully elucidated. In an effort to determine these parameters, we compared the ability of different Laccases for the oxidation of lignin model compounds in a Laccase-mediator system. More specifically, four Laccases from different fungal species were purified and used to oxidize the β-O-4 dimer I (the most predominant lignin substructure) and phenol red (a phenolic lignin model compound). Laccases from the different sources were found to oxidize dimer I and phenol red at different rates. Criteria for a better Laccase and more effective Laccase-mediator systems for pulp bleaching have been suggested.
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molecular analysis of a Laccase gene from the white rot fungus pycnoporus cinnabarinus
Applied and Environmental Microbiology, 1998Co-Authors: Claudia Eggert, Ulrike Temp, Karlerik Eriksson, Peter R Lafayette, Jeffrey F D DeanAbstract:By definition, Laccases (p-diphenol:O2 oxidoreductase; EC 1.10.3.2) catalyze the oxidation of p-diphenols and the concurrent reduction of dioxygen to water, although the actual substrate specificities of Laccases are often quite broad and vary with the enzyme source (11, 29). Laccases are members of the blue copper oxidase enzyme family characterized by having four cupric (Cu2+) ions coordinated such that each of the known magnetic species (type 1, type 2, and type 3) is associated with a single polypeptide chain. The Cu2+-binding domains are highly conserved in the blue copper oxidases, and the crystallographic structure of ascorbate oxidase, another member of this enzyme class, has provided a good model for the structure of the Laccase active site (30, 31). This model has been supported by the results of numerous studies of the electron transfer reactions that occur between cupric ions during catalysis (35, 39, 40). In contrast to our understanding of the electron transfer reactions that occur in Laccases, relatively little is known about the physiological functions of these enzymes. Laccases have been implicated in pigmentation (1, 9), fruiting body formation (26), and pathogenicity (7, 45), as well as in lignin degradation (41) and biosynthesis (27). Very few of these functions have been experimentally proven, and only because of the availability of multiple gene sequences and crystallographic data has it been possible to speculate about how structure-function relationships may be important in the specific roles played by these enzymes (46). Some of this speculation has involved attempts to address the apparent contradictory functions of Laccases in the synthesis and breakdown of lignin (3, 11). To better understand the role of Laccases in lignin degradation by white rot fungi, we studied the ligninolytic system of Pycnoporus cinnabarinus, a basidiomycete that produces an unusual set of ligninolytic enzymes. Just a single isoform of Laccase, but no lignin peroxidase (LiP) or manganese peroxidase (MnP), was produced by this organism under conditions that stimulated lignin degradation (13). We wanted to determine more completely the pattern of phenoloxidase production in P. cinnabarinus, so the primary objective of this study was to analyze the structure of the P. cinnabarinus Laccase gene and determine whether there are multiple Laccase genes in the P. cinnabarinus genome.
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a fungal metabolite mediates degradation of non phenolic lignin structures and synthetic lignin by Laccase
FEBS Letters, 1996Co-Authors: Claudia Eggert, Ulrike Temp, Jeffrey F D Dean, Karlerik ErikssonAbstract:Lignin peroxidase is generally considered to be a primary catalyst for oxidative depolymerization of lignin by white-rot fungi. However, some white-rot fungi lack lignin peroxidase. Instead, many produce Laccase, even though the redox potentials of known Laccases are two to directly oxidize non-phenolic components of lignin. Pycnoporus cinnabarinus is one example of a Laccase-producing fungus that degrades lignin very efficiently. To overcome the redox potential barrier, P. cinnabarinus produces a metabolite, 3-hydroxyanthranilate that can mediate the oxidation of non-phenolic substrates by Laccase. This is the first description of how Laccase might function in a biological system for the complete depolymerization of lignin.
Artur Cavacopaulo - One of the best experts on this subject based on the ideXlab platform.
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degradation of azo dyes by trametes villosa Laccase over long periods of oxidative conditions
Applied and Environmental Microbiology, 2005Co-Authors: Andrea Zille, Barbara Gornacka, Astrid Rehorek, Artur CavacopauloAbstract:Trametes villosa Laccase was used for direct azo dye degradation, and the reaction products that accumulated after 72 h of incubation were analyzed. Liquid chromatography-mass spectrometry (LC-MS) analysis showed the formation of phenolic compounds during the dye oxidation process as well as a large amount of polymerized products that retain azo group integrity. The amino-phenol reactions were also investigated by 13C-nuclear magnetic resonance and LC-MS analysis, and the polymerization character of Laccase was shown. This study highlights the fact that Laccases polymerize the reaction products obtained during long-term batch decolorization processes with azo dyes. These polymerized products provide unacceptable color levels in effluents, limiting the application of Laccases as bioremediation agents.
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an acid stable Laccase from sclerotium rolfsii with potential for wool dye decolourization
Enzyme and Microbial Technology, 2003Co-Authors: Stephanie E Ryan, Artur Cavacopaulo, Wolfgang Schnitzhofer, Tzanko Tzanov, Georg GubitzAbstract:Abstract The plant pathogen basidiomycete S. rolfsii secretes two Laccases (SRL1 and SRL2) with molecular weights of 55 and 86 kDa, respectively. Laccase production was shown to be inducible by the addition of 2,5-xylidine to the cultural media. After treatment with a combination of chitinase and β-1,3-glucanase, two different Laccases were isolated from the sclerotia depending on the stage of sclerotia development. The more prominent Laccase, SRL1, was purified and found to decolourize the industrially important wool azo dye Diamond Black PV 200 without the addition of redox mediators. The enzyme (pI 5.2) was active in the acidic pH range, showing an optimal activity at pH 2.4, with ABTS as substrate. The optimum temperature for activity was determined to be 62 °C. Enzyme stability studies revealed that SRL1 was notably stable at 18 °C and pH 4.5, retaining almost full activity after a week. Oxidation of tyrosine was not detectable under the reaction conditions but the enzyme did oxidize a variety of the usual Laccase substrates. SRL1 was strongly inhibited by sodium azide and fluoride. Dye solutions decolourized with the immobilized Laccase were successfully used for redyeing.
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indigo degradation with purified Laccases from trametes hirsuta and sclerotium rolfsii
Journal of Biotechnology, 2001Co-Authors: Rui Campos, Karlheinz Robra, Artur Cavacopaulo, Andreas Kandelbauer, Georg GubitzAbstract:The degradation of the textile dye indigo with purified Laccases from the fungi Trametes hirsuta (THL1 and THL2) and Sclerotium rolfsii (SRL1) was studied. All Laccases were able to oxidize indigo yielding isatin (indole-2,3-dione), which was further decomposed to anthranilic acid (2-aminobenzoic acid). Based on the oxygen consumption rate of the Laccases during indigo degradation, a potential mechanism for the oxidation of indigo involving the step-wise abstraction of four electrons from indigo by the enzyme was suggested. Comparing the effect of the known redox-mediators acetosyringone, 1-hydroxybenzotriazole (HOBT) and 4-hydroxybenzenesulfonic acid (PHBS) on Laccase-catalyzed degradation of indigo, we found a maximum of about 30% increase in the oxidation rate of indigo with SRL1 and acetosyringone. The particle size of indigo agglomerates after Laccase treatment was influenced by the origin of the Laccase preparation and by the incubation time. Diameter distributions were found to have one maximum and compared to the indigo particle size distribution of the control, for all Laccases, the indigo agglomerates seemed to have shifted to smaller diameters. Bleaching of fabrics by the Laccases (based on K/S values) correlated with the release of indigo degradation products.
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indigo degradation with Laccases from polyporus sp and sclerotium rolfsii
Textile Research Journal, 2001Co-Authors: Rui Campos, Monika Schneider, Karlheinz Robra, Artur Cavacopaulo, Georg GubitzAbstract:We have investigated the potential of fungal Laccases from Polyporus sp. and Sclerotium rolfsii to degrade insoluble indigo. Evidence shows that both Laccases are able to oxidize insoluble indigo to give isatin (indole-2,3-dione), which further degrades to anthranilic acid (2-aminobenzoic acid). Adsorption studies show that the Laccase from Polyporus sp. has a higher affinity for indigo than the Laccase of Sclerotium rolfsii. The particle size of indigo agglomerates is influenced by the origin of the Laccase preparation and the incubation time. The potential of Laccases to modify indigo stained fabrics is assessed. Treatment of indigo dyed fabrics with Laccase prevents indigo backstaining, and Polyporus sp. appears to be more effective for reducing backstaining.
Jeffrey F D Dean - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis of a Laccase gene from the white rot fungus pycnoporus cinnabarinus
Applied and Environmental Microbiology, 1998Co-Authors: Claudia Eggert, Ulrike Temp, Karlerik Eriksson, Peter R Lafayette, Jeffrey F D DeanAbstract:By definition, Laccases (p-diphenol:O2 oxidoreductase; EC 1.10.3.2) catalyze the oxidation of p-diphenols and the concurrent reduction of dioxygen to water, although the actual substrate specificities of Laccases are often quite broad and vary with the enzyme source (11, 29). Laccases are members of the blue copper oxidase enzyme family characterized by having four cupric (Cu2+) ions coordinated such that each of the known magnetic species (type 1, type 2, and type 3) is associated with a single polypeptide chain. The Cu2+-binding domains are highly conserved in the blue copper oxidases, and the crystallographic structure of ascorbate oxidase, another member of this enzyme class, has provided a good model for the structure of the Laccase active site (30, 31). This model has been supported by the results of numerous studies of the electron transfer reactions that occur between cupric ions during catalysis (35, 39, 40). In contrast to our understanding of the electron transfer reactions that occur in Laccases, relatively little is known about the physiological functions of these enzymes. Laccases have been implicated in pigmentation (1, 9), fruiting body formation (26), and pathogenicity (7, 45), as well as in lignin degradation (41) and biosynthesis (27). Very few of these functions have been experimentally proven, and only because of the availability of multiple gene sequences and crystallographic data has it been possible to speculate about how structure-function relationships may be important in the specific roles played by these enzymes (46). Some of this speculation has involved attempts to address the apparent contradictory functions of Laccases in the synthesis and breakdown of lignin (3, 11). To better understand the role of Laccases in lignin degradation by white rot fungi, we studied the ligninolytic system of Pycnoporus cinnabarinus, a basidiomycete that produces an unusual set of ligninolytic enzymes. Just a single isoform of Laccase, but no lignin peroxidase (LiP) or manganese peroxidase (MnP), was produced by this organism under conditions that stimulated lignin degradation (13). We wanted to determine more completely the pattern of phenoloxidase production in P. cinnabarinus, so the primary objective of this study was to analyze the structure of the P. cinnabarinus Laccase gene and determine whether there are multiple Laccase genes in the P. cinnabarinus genome.
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a fungal metabolite mediates degradation of non phenolic lignin structures and synthetic lignin by Laccase
FEBS Letters, 1996Co-Authors: Claudia Eggert, Ulrike Temp, Jeffrey F D Dean, Karlerik ErikssonAbstract:Lignin peroxidase is generally considered to be a primary catalyst for oxidative depolymerization of lignin by white-rot fungi. However, some white-rot fungi lack lignin peroxidase. Instead, many produce Laccase, even though the redox potentials of known Laccases are two to directly oxidize non-phenolic components of lignin. Pycnoporus cinnabarinus is one example of a Laccase-producing fungus that degrades lignin very efficiently. To overcome the redox potential barrier, P. cinnabarinus produces a metabolite, 3-hydroxyanthranilate that can mediate the oxidation of non-phenolic substrates by Laccase. This is the first description of how Laccase might function in a biological system for the complete depolymerization of lignin.
Claudia Eggert - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis of a Laccase gene from the white rot fungus pycnoporus cinnabarinus
Applied and Environmental Microbiology, 1998Co-Authors: Claudia Eggert, Ulrike Temp, Karlerik Eriksson, Peter R Lafayette, Jeffrey F D DeanAbstract:By definition, Laccases (p-diphenol:O2 oxidoreductase; EC 1.10.3.2) catalyze the oxidation of p-diphenols and the concurrent reduction of dioxygen to water, although the actual substrate specificities of Laccases are often quite broad and vary with the enzyme source (11, 29). Laccases are members of the blue copper oxidase enzyme family characterized by having four cupric (Cu2+) ions coordinated such that each of the known magnetic species (type 1, type 2, and type 3) is associated with a single polypeptide chain. The Cu2+-binding domains are highly conserved in the blue copper oxidases, and the crystallographic structure of ascorbate oxidase, another member of this enzyme class, has provided a good model for the structure of the Laccase active site (30, 31). This model has been supported by the results of numerous studies of the electron transfer reactions that occur between cupric ions during catalysis (35, 39, 40). In contrast to our understanding of the electron transfer reactions that occur in Laccases, relatively little is known about the physiological functions of these enzymes. Laccases have been implicated in pigmentation (1, 9), fruiting body formation (26), and pathogenicity (7, 45), as well as in lignin degradation (41) and biosynthesis (27). Very few of these functions have been experimentally proven, and only because of the availability of multiple gene sequences and crystallographic data has it been possible to speculate about how structure-function relationships may be important in the specific roles played by these enzymes (46). Some of this speculation has involved attempts to address the apparent contradictory functions of Laccases in the synthesis and breakdown of lignin (3, 11). To better understand the role of Laccases in lignin degradation by white rot fungi, we studied the ligninolytic system of Pycnoporus cinnabarinus, a basidiomycete that produces an unusual set of ligninolytic enzymes. Just a single isoform of Laccase, but no lignin peroxidase (LiP) or manganese peroxidase (MnP), was produced by this organism under conditions that stimulated lignin degradation (13). We wanted to determine more completely the pattern of phenoloxidase production in P. cinnabarinus, so the primary objective of this study was to analyze the structure of the P. cinnabarinus Laccase gene and determine whether there are multiple Laccase genes in the P. cinnabarinus genome.
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a fungal metabolite mediates degradation of non phenolic lignin structures and synthetic lignin by Laccase
FEBS Letters, 1996Co-Authors: Claudia Eggert, Ulrike Temp, Jeffrey F D Dean, Karlerik ErikssonAbstract:Lignin peroxidase is generally considered to be a primary catalyst for oxidative depolymerization of lignin by white-rot fungi. However, some white-rot fungi lack lignin peroxidase. Instead, many produce Laccase, even though the redox potentials of known Laccases are two to directly oxidize non-phenolic components of lignin. Pycnoporus cinnabarinus is one example of a Laccase-producing fungus that degrades lignin very efficiently. To overcome the redox potential barrier, P. cinnabarinus produces a metabolite, 3-hydroxyanthranilate that can mediate the oxidation of non-phenolic substrates by Laccase. This is the first description of how Laccase might function in a biological system for the complete depolymerization of lignin.
Angel T Martinez - One of the best experts on this subject based on the ideXlab platform.
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lignin degradation and detoxification of eucalyptus wastes by on site manufacturing fungal enzymes to enhance second generation ethanol yield
Applied Energy, 2020Co-Authors: Willian Daniel Hahn Schneider, Maria Jesus Martinez, Roselei Claudete Fontana, Henrique Macedo Baudel, Felix Goncalves De Siqueira, Jorge Rencoret, Ana Gutierrez, Laura I De Eugenio, Alicia Prieto, Angel T MartinezAbstract:Abstract Novel Laccases have promising and valuable applications in biorefineries. This investigation documents, for the first time, the potential of depolymerising and repolymerising lignin by the secretome, rich in Laccases, from a newly isolated white-rot basidiomycete Marasmiellus palmivorus VE111, for further saccharification and ethanolic fermentation steps. Proteomic analyses of the secretome of M. palmivorus show that Laccases are the most predominant enzyme released by this fungus. The whole crude enzymatic broth is used for the delignification of lignin in Eucalyptus globulus wood, with the aim of enhancing the saccharification by cellulolytic and xylanolytic enzymes from Penicillium echinulatum S1M29. In addition, two different strategies, namely, Laccase treatment before and after enzymatic hydrolysis, are employed to detoxify steam-exploded E. globulus wood. The objective is to increase the fermentative performance by removing substances formed during the feedstock pretreatment that can inhibit microbial fermentation. The E. globulus wood delignification results in a 31% decrease in the lignin content and a 10% increase in the glucose yield after hydrolysis. An important finding of the present work is the successful wood delignification in the absence of Laccase mediators. This Laccase-rich preparation also demonstrates its potential in removing the phenolic inhibitors present in steam-exploded E. globulus wood, increasing the ethanol yield by an additional 10%. Furthermore, it is important to highlight that these findings are achieved in the absence of commercial enzymes, making M. palmivorus Laccases a potential candidate not only for the production of biofuels but also for the generation of lignin-derived aromatic compounds for different applications in the biotechnology industry.
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efficient bleaching of non wood high quality paper pulp using Laccase mediator system
Enzyme and Microbial Technology, 2004Co-Authors: Susana Camarero, Maria Jesus Martinez, Ana Gutierrez, O Garcia, Teresa Vidal, Jose F Colom, Jose M Gras, Rebeca Monje, Angel T MartinezAbstract:High-quality flax pulp was bleached in a totally-chlorine-free (TCF) sequence using a Laccase-mediator system. Three fungal Laccases (from Pycnoporus cinnabarinus , Trametes versicolorand Pleurotus eryngii) and two mediators, 2,2 � -azinobis(3-ethylbenzothiazoline-6sulfonic acid) and 1-hydroxybenzotriazole (HBT), were compared. P. cinnabarinusand T. versicolor Laccases in the presence of HBT gave the best results in terms of high brightness and low lignin content (kappa number). The former Laccase also resulted in the best preservation of cellulose and the largest removal of residual lignin as revealed by analytical pyrolysis, and was selected for subsequent TCF bleaching. Up to 90% delignification and strong brightness increase were attained after a Laccase-mediator treatment followed by H 2O2 bleaching. This TCF sequence was further improved by applying H2O2 under pressurized O2. In this way, we obtained up to 82% ISO brightness (compared with 37% in the initial pulp, and 60% in the peroxide-bleached control) and very low kappa number (near 1). Good results were also found when the Laccase-mediator treatment was performed in a bioreactor under pressurized oxygen. The pulp properties obtained, which could not be attained by conventional TCF bleaching of flax pulp, demonstrate the feasibility of enzymatic bleaching to substitute chlorine-containing reagents in manufacturing of these high-price paper pulps.
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Laccase isoenzymes of pleurotus eryngii characterization catalytic properties and participation in activation of molecular oxygen and mn2 oxidation
Applied and Environmental Microbiology, 1997Co-Authors: Carmen Munoz, Francisco Guillen, Angel T Martinez, Maria Jesus MartinezAbstract:Two Laccase isoenzymes produced by Pleurotus eryngii were purified to electrophoretic homogeneity (42- and 43-fold) with an overall yield of 56.3%. Laccases I and II from this fungus are monomeric glycoproteins with 7 and 1% carbohydrate content, molecular masses (by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of 65 and 61 kDa, and pIs of 4.1 and 4.2, respectively. The highest rate of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) oxidation for Laccase I was reached at 65 degrees C and pH 4, and that for Laccase II was reached at 55 degrees C and pH 3.5. Both isoenzymes are stable at high pH, retaining 60 to 70% activity after 24 h from pH 8 to 12. Their amino acid compositions and N-terminal sequences were determined, the latter strongly differing from those of Laccases of other basidiomycetes. Antibodies against Laccase I reacted with Laccase II, as well as with Laccases from Pleurotus ostreatus, Pleurotus pulmonarius, and Pleurotus floridanus. Different hydroxy- and methoxy-substituted phenols and aromatic amines were oxidized by the two Laccase isoenzymes from P. eryngii, and the influence of the nature, number, and disposition of aromatic-ring substituents on kinetic constants is discussed. Although both isoenzymes presented similar substrate affinities, the maximum rates of reactions catalyzed by Laccase I were higher than those of Laccase II. In reactions with hydroquinones, semiquinones produced by Laccase isoenzymes were in part converted into quinones via autoxidation. The superoxide anion radical produced in the latter reaction dismutated, producing hydrogen peroxide. In the presence of manganous ion, the superoxide union was reduced to hydrogen peroxide with the concomitant production of manganic ion. These results confirmed that Laccase in the presence of hydroquinones can participate in the production of both reduced oxygen species and manganic ions.
