Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.2 (laccase)
 4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ultrafiltered low-molecular-weight preparation of chelating compounds was isolated from a wood-containing culture of the white-rot basidiomycete Coriolus versicolor. This preparation could chelate Fe3+ and reduce Fe3+ to Fe2+, demonstrating that the substance may serve as a ferric chelator, oxygen-reducing agent, and redox-cycling molecule, which would include functioning as the electron transport carrier in Fenton reaction. Lignin was treated with the iron-binding chelator and the changes in structure were investigated by 1H-NMR, 13C-NMR, difference spectrum caused by ionization under alkaline conditions and nitrobenzene oxidation. The results indicated that the iron-binding chelator could destroy the beta-O-4 bonds in etherified lignin units and insert phenolic hydroxyl groups. The low-molecular-weight chelator secreted by C. versicolor resulted in new phenolic substructures in the lignin polymer, making it susceptible to attack by laccase or manganese peroxidase. Thus, the synergic action of the iron-binding chelator and the lignocellulolytic enzymes made the substrate more accessible to degradation.
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PMID:Function of the iron-binding chelator produced by Coriolus versicolor in lignin biodegradation. 1824 9

The white rot fungus Trametes versicolor is an efficient lignin degrader with ecological significance and industrial applications. Lignin-modifying enzymes of white rot fungi are mainly produced during secondary metabolism triggered in these microorganisms by nutrient deprivation. Selective ubiquitin/proteasome-mediated proteolysis is known to play a crucial role in the response of cells to various stresses such as nutrient limitation, heat shock, and heavy metal exposure. Previous studies from our laboratory demonstrated that proteasomal degradation of intracellular proteins is involved in the regulation of laccase, a major ligninolytic enzyme of T. versicolor, in response to cadmium. In the present study, it was found that the 6-h nitrogen starvation leads to depletion of intracellular free ubiquitin pool in T. versicolor. The difference in the intracellular level of free monomeric ubiquitin observed between the mycelium extract from the nitrogen-deprived and that from the nitrogen-sufficient culture was accompanied by the different pattern of ubiquitin-dependent degradation. Furthermore, it was found that nitrogen deprivation affected 26S proteasome activities of T. versicolor. Proteasome inhibition by lactacystin beta-lactone, a highly specific agent, increased laccase activity in nitrogen-deprived cultures, but not in nitrogen-sufficient cultures. The present study implicates the ubiquitin/proteasome-mediated proteolytic pathway in the response of T. versicolor to nitrogen deprivation.
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PMID:The role of the ubiquitin-proteasome system in the response of the ligninolytic fungus Trametes versicolor to nitrogen deprivation. 1827 47

The production of biomass and ligninolytic enzymes by Pleurotus ostreatus was analysed in synthetic medium with yeast extract and different glucose concentrations (0.5 - 20 g/l), at different pH (3.5-6.5) and incubation temperatures (23-32 degrees C). The best culture condition were: initial glucose concentration of 5 g/l, initial pH between 5.5-6.5 and incubation temperature between 26-29 degrees C. The saturation constant for glucose (Ks) was 1.75 g/l. The biomass concentration reached 8.6 g/l with a glucose addition of 20.0 g/l to the culture medium. The control of pH allowed an increment of 0.5 g/l of biomass concentration. The birreactor produced pellets with a homogeneous distribution of diameter size of 3.4 -/+ 0.2 mm. Approximately, 307 U/l of laccase and 0.41 U/l of manganese peroxidase were obtained in extracellular liquid medium and 0.015 U/g of laccase and 0.809 U/g of manganese peroxidase were obtained in solid substrate. Lignin peroxidase activity was not detected at any condition.
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PMID:[Production of biomass and ligninolytic enzymes by Pleurotus ostreatus in submerged culture.]. 1847 24

A strict screening strategy for microorganism selection was followed employing a number of white-rot fungi for the bioremediation of textile effluent, which was generated from one Ireland-based American textile industry. Finally, one fungus Bjerkandera adusta has been investigated in depth for its ability to simultaneously degrade and enrich the nutritional quality of highly coloured textile effluent-adsorbed barley husks through solid-state fermentation (SSF). Certain important parameters such as media requirements, moisture content, protein/biomass production and enzyme activities were examined in detail. A previously optimised method of dye desorption was employed to measure the extent of dye remediation through effluent decolorisation achieved as a result of fungal activity in SSF. B. adusta was capable of decolourising a considerable concentration of the synthetic dye effluent (up to 53%) with a moisture content of 80-85%. Protein enrichment of the fermented mass was achieved to the extent of 229 g/kg dry weight initial substrate used. Lignin peroxidase and laccase were found to be the two main enzymes produced during SSF of the dye-adsorbed lignocellulosic waste residue.
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PMID:Remediation of textile dye waste water using a white-rot fungus Bjerkandera adusta through solid-state fermentation (SSF). 1849 71

Lignin is amorphous in nature, lacks stereoregularity, and is not susceptible to hydrolytic attack. Despite its resistant nature, it is however degraded by various microorganisms, particularly, white-rot fungi. Such fungi are capable of extracellular production of lignin peroxidase, manganese peroxidase, and laccase, the three major enzymes associated with ligninolysis. Though all white-rot fungi do not produce all the three enzymes, laccase occupies an important place in ligninolysis. Laccase belongs to a diverse group of enzymes called oxidoreductases and is also known as benzenediol: oxygen oxidoreductase. They have low substrate specificity. The copper-containing enzyme laccase has been detected in a variety of organisms such as bacteria, fungi, plants, and insects. Mostly, these are extracellular proteins, although intracellular laccases have also been detected in some fungi and insects. Fungal laccases are believed to play a variety of roles, such as, morphogenesis, pathogenesis, and lignin degradation. As an oxidase, laccase is used in many agricultural, industrial, and medicinal applications. Current investigations are focused on laccase-based biooxidation, biotransformation, biosensor, and enzymatic synthesis of organic compounds. By enhancing laccase production using different physiochemical parameters, better understanding of the mechanism for the reactions of interest, and optimizing the catalytic activity of laccase, it can be used in a better way in diverse fields of biotechnology.
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PMID:Ligninolytic fungal laccases and their biotechnological applications. 1951 57

White-rot fungi are of interest due to their ability to degrade lignin. Lignin-degrading enzymes such as laccase can also degrade xenobiotic compounds. The effects of interspecific interactions between white-rot fungi and other microorganisms on laccase activity was studied in laboratory cultures. Laccase activity in cultures of Trametes versicolor and Pleurotus ostreatus increased significantly after the introduction of soil fungi, bacteria and yeasts or after contact with nonsterile soil. Addition of Trichoderma harzianum to cultures of T. versicolor increased laccase activity more than 40 fold, whereas addition of other soil fungi or bacteria resulted in 2-25 fold increases and the addition of soil or soil extracts led to 10-15 fold increases. No laccase induction was detected after addition of heat or filter-sterilized microbial cultures, soil or soil extract. Increased decolorization of the synthetic dye Remazol Brilliant Blue R occurred in mixed cultures. When T. versicolor was cocultured with other soil microorganisms, the number of colony forming units of the other soil microbes decreased. This effect could not be shown to be caused by laccase. In 16 of 24 species of white-rot fungi tested, laccase increased following the addition of T. harzianum. The increase was only absent in species with no or low laccase production. Co-inoculation of P. ostreatus and T. versicolor resulted in an increase of laccase in the mixed culture.
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PMID:Increase of laccase activity during interspecific interactions of white-rot fungi. 1971 64

Lignin composition (monolignol types of coniferyl, sinapyl or p-coumaryl alcohol) is causally related to biomass recalcitrance. We describe multiwavelength (220, 228, 240, 250, 260, 290, 295, 300, 310 or 320 nm) absorption spectroscopy of coniferyl alcohol and its laccase- or peroxidase-catalyzed products during real time kinetic, pseudokinetic and endpoint analyses, in optical turn on or turn off modes, under acidic or basic conditions. Reactions in microwell plates and 100 microL volumes demonstrated assay miniaturization and high throughput screening capabilities. Bathochromic and hypsochromic shifts along with hyperchromicity or hypochromicity accompanied enzymatic oxidations by laccase or peroxidase. The limits of detection and quantitation of coniferyl alcohol averaged 2.4 and 7.1 muM respectively, with linear trend lines over 3 to 4 orders of magnitude. Coniferyl alcohol oxidation was evident within 10 minutes or with 0.01 microg/mL laccase and 2 minutes or 0.001 microg/mL peroxidase. Detection limit improved to 1.0 microM coniferyl alcohol with Km of 978.7 +/- 150.7 microM when examined at 260 nm following 30 minutes oxidation with 1.0 microg/mL laccase. Our assays utilized the intrinsic spectroscopic properties of coniferyl alcohol or its oxidation products for enabling detection, without requiring chemical synthesis or modification of the substrate or product(s). These studies facilitate lignin compositional analyses and augment pretreatment strategies for reducing biomass recalcitrance.
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PMID:Spectroscopic analyses of the biofuels-critical phytochemical coniferyl alcohol and its enzyme-catalyzed oxidation products. 1993 74

The aim of the present study was to compare the effect of a wide range of culture conditions on production of ligninolytic enzymes by Polyporus sanguineus and Phanerochaete chrysosporium. Lignin peroxidase production by P. sanguineus was comparable with that of P. chrysosporium, although the culture conditions giving the highest yield varied greatly between the two fungi. Highest yield of manganese peroxidase by P. sanguineus obtained in 0.5% malt extract medium and peptone or malt extract supplemented mineral salts broth could not be surpassed by P. chrysosporium in any of the optimization experiments. In addition to lignin peroxidase and manganese peroxidase, P. sanguineus also produced laccase, which was best expressed in malt extract medium supplemented with sugarcane bagasse.
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PMID:Comparative production of ligninolytic enzymes by Phanerochaete chrysosporium and Polyporus sanguineus. 2002 32

A long-term field experiment conducted in a Norway spruce forest at Solling, Central Germany, was used to verify and compare the response of lignin-decomposing fungal communities in soils receiving current and preindustrial atmospheric nitrogen (N) input for 14.5 years. Therefore, we investigated the decomposition of lignin compounds in relation to phenol oxidase activity and the diversity of basidiomycetes containing laccase genes in organic and mineral horizons. Lignin-derived CuO oxidation products and enzyme activity decreased with soil depth, while the degree of oxidative transformation of lignin increased. These patterns did not change with reduced atmospheric N input, likely reflecting a lasting saturation in available N. The laccase gene diversity decreased with soil depth in spring. In autumn, this pattern was only found in the control plot, receiving current N input. Principal component analysis confirmed the depth profile and distinguished a response of the fungal community to reduced N deposition for most organic layers in spring and a roof effect for the Oe layer in autumn. These responses of the fungal community did not translate into changes in enzyme activity and lignin content and decomposition, suggesting that transformation processes in soils are well buffered despite the rapid response of the microbial community to environmental factors.
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PMID:Response of recalcitrant soil substances to reduced N deposition in a spruce forest soil: integrating laccase-encoding genes and lignin decomposition. 2049 21

This research was carried out to study the treatment of landfill leachate by immobilized Trametes versicolor BCC 8725. Leachate was collected from Nonthaburi disposal site of Thailand from a pipe as discharged from landfill to the stabilization pond. Batch experiments were conducted to determine the effects of carbon source (glucose) on the biomass growth of fungi and the treatment of leachate in terms of color, Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) removal. Enzymes produced by Trametes versicolor BCC 8725 were also analyzed. Experimental results indicated a higher biomass growth when glucose was added, indicating that the growth of fungi is dependent on the co-substrate. The percentage of color removal is approximately 58% and 12%, respectively, with and without glucose. BOD and COD removals were 37% and 40% with glucose addition within 12 days at optimum conditions. Enzyme analysis indicated that laccase was the main enzyme produced. In addition, Manganese Peroxidase (MnP) and Lignin Peroxidase (LiP) were also detected. The fungi were able to produce the enzymes. The peak concentrations of LiP, MnP and laccase activity were found to be 384, 1,241, 2,534 unit/litre (U/L) with glucose, indicating that the color removal rates were proportional to the enzyme activity.
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PMID:Effect of glucose on enzyme activity and color removal by Trametes versicolor for high strength landfill leachate. 2109 37


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