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)

A new microheterogeneous non-aqueous medium for enzymatic reactions, based on reversed micelles of a polymeric surfactant, was suggested. The surfactant termed CEPEI, was synthesized by successive alkylation of poly(ethyleneimine) with cetyl bromide and ethyl bromide and was found to be able to solubilize considerable amounts of water in benzene/n-butanol mixtures. The hydrodynamic radius of polymeric-reversed micelles was estimated to be in the range 22-51 nm, depending on the water content of the system, as determined by means of the quasi-elastic laser-light scattering. Polymeric reversed micelles were capable of solubilizing enzymes (alpha-chymotrypsin and laccase) in nonpolar solvents with retention of catalytic activity. Due to the strong buffering properties of CEPEI over a wide pH range, it could maintain any adjusted pH inside hydrated reversed micelles. It was found that catalytic behavior of enzymes entrapped in polymeric reversed micelles was rather insensitive to the pH of the buffer solution introduced into the system as an aqueous component, but determined mostly by acid-base properties of the polymeric surfactant itself. Both catalytic activity and stability of entrapped alpha-chymotrypsin and laccase were found to increase with increasing water content of the system. Under certain conditions, the entrapment of alpha-chymotrypsin into CEPEI reversed micelles resulted in a considerable increase in catalytic activity and stability as compared to aqueous solution. CEPEI reversed micelles were demonstrated to be promising enzyme carriers for use in membrane reactors. Owing to the large dimensions of CEPEI reversed micelles, they are effectively kept back by a semipermeable membrane, thus allowing an easy separation of the reaction product and convenient recovery of the enzyme.
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PMID:Reversed micelles of polymeric surfactants in nonpolar organic solvents. A new microheterogeneous medium for enzymatic reactions. 160 58

Galactomyces geotrichum MTCC 1360 degraded the Scarlet RR (100 mg/l) dye within 18 h, under shaking conditions (150 rpm) in malt yeast medium. The optimum pH and the temperature for decolorization were pH 12 and 50 degrees , respectively. Enzymatic studies revealed an induction of the enzymes, including flavin reductase during the initial stage and lignin peroxidase after complete decolorization of the dye. Decolorization of the dye was induced by the addition of CaCO3 to the medium. EDTA had an inhibitory effect on the dye decolorization along with the laccase activity. The metabolites formed after complete decolorization were analyzed by UV-VIS, HPLC, and FTIR. The GC/MS identification of 3 H quinazolin-4- one, 2-ethylamino-acetamide, 1-chloro-4-nitro-benzene, N- (4-chloro-phenyl)-hydroxylamine, and 4-chloro-pheny-lamine as the final metabolites corroborated with the degradation pathway is suggested to understand the mechanism used by G.geotrichum and thereby aiding development of technologies for the application of this organism to the cleaning-up of aquatic and terrestrial environments.
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PMID:Degradation and detoxification of disperse dye Scarlet RR by Galactomyces geotrichum MTCC 1360. 1942 Sep 99

PAHs are aromatic hydrocarbons with two or more fused benzene rings with natural as well as anthropogenic sources. They are widely distributed environmental contaminants that have detrimental biological effects, toxicity, mutagenecity and carcinogenicity. Due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity, the PAHs have gathered significant environmental concern. Although PAH may undergo adsorption, volatilization, photolysis, and chemical degradation, microbial degradation is the major degradation process. PAH degradation depends on the environmental conditions, number and type of the microorganisms, nature and chemical structure of the chemical compound being degraded. They are biodegraded/biotransformed into less complex metabolites, and through mineralization into inorganic minerals, H(2)O, CO(2) (aerobic) or CH(4) (anaerobic) and rate of biodegradation depends on pH, temperature, oxygen, microbial population, degree of acclimation, accessibility of nutrients, chemical structure of the compound, cellular transport properties, and chemical partitioning in growth medium. A number of bacterial species are known to degrade PAHs and most of them are isolated from contaminated soil or sediments. Pseudomonas aeruginosa, Pseudomons fluoresens, Mycobacterium spp., Haemophilus spp., Rhodococcus spp., Paenibacillus spp. are some of the commonly studied PAH-degrading bacteria. Lignolytic fungi too have the property of PAH degradation. Phanerochaete chrysosporium, Bjerkandera adusta, and Pleurotus ostreatus are the common PAH-degrading fungi. Enzymes involved in the degradation of PAHs are oxygenase, dehydrogenase and lignolytic enzymes. Fungal lignolytic enzymes are lignin peroxidase, laccase, and manganese peroxidase. They are extracellular and catalyze radical formation by oxidation to destabilize bonds in a molecule. The biodegradation of PAHs has been observed under both aerobic and anaerobic conditions and the rate can be enhanced by physical/chemical pretreatment of contaminated soil. Addition of biosurfactant-producing bacteria and light oils can increase the bioavailability of PAHs and metabolic potential of the bacterial community. The supplementation of contaminated soils with compost materials can also enhance biodegradation without long-term accumulation of extractable polar and more available intermediates. Wetlands, too, have found an application in PAH removal from wastewater. The intensive biological activities in such an ecosystem lead to a high rate of autotrophic and heterotrophic processes. Aquatic weeds Typha spp. and Scirpus lacustris have been used in horizontal-vertical macrophyte based wetlands to treat PAHs. An integrated approach of physical, chemical, and biological degradation may be adopted to get synergistically enhanced removal rates and to treat/remediate the contaminated sites in an ecologically favorable process.
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PMID:Biodegradation aspects of polycyclic aromatic hydrocarbons (PAHs): a review. 1944 41

Laccase/mediator systems are important bioremediation agents as the rates of reactions can be enhanced in the presence of the mediators. The decolorization mechanism of two triarylmethane dyes, namely, Basic Green 4 and Acid Violet 17 is reported using Cyathus bulleri laccase. Basic Green 4 was decolorized through N-demethylation by laccase alone, while in mediator assisted reactions, dye breakdown was initiated from oxidation of carbinol form of the dye. Benzaldehyde and N,N-dimethyl aniline were the major end products. With Acid Violet 17, laccase carried out N-deethylation and in mediator assisted reactions, oxidation of the carbinol form of the dye occurred resulting in formation of formyl benzene sulfonic acid, carboxy benzene sulfonic acid and benzene sulfonic acid. Toxicity analysis revealed that Basic Green 4 was toxic and treatment with laccase/mediators resulted in 80-100% detoxification. The treatment of the textile dye solution using laccase and 2,2'-azino-di-(-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was demonstrated in an enzyme membrane reactor. At a hydraulic retention time of 6h, the process was operated for a period of 15 days with nearly 95% decolorization, 10% reduction in flux and 70% recovery of active ABTS.
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PMID:Laccase/mediator assisted degradation of triarylmethane dyes in a continuous membrane reactor. 1953 71

We found that acetaminophen could be effectively transformed and removed from water by laccase-mediated oxidative coupling processes. The removal of acetaminophen followed second-order kinetics with first-order to the concentrations of both the substrate and the enzyme. Mass spectrum analysis demonstrated that polymerization through radical-radical coupling mechanism was the pathway leading to acetaminophen transformation. Coupling products thus formed are believed to be biologically inactive and more readily removable from water. Secondary mass spectra of the dimers in combination with molecular modeling analysis further elucidated that the coupling proceeded via covalent bonding between two molecules at their unsubstituted carbons in benzene rings. These findings demonstrated that laccase-mediated oxidative coupling can potentially serve as an alternative strategy to control certain micropollutants in water/wastewater treatment and reuse.
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PMID:Removal of acetaminophen using enzyme-mediated oxidative coupling processes: I. Reaction rates and pathways. 1980 42

Advanced oxidation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) by the extracellular hydroxyl radicals (*OH) generated by the white-rot fungus Trametes versicolor is for the first time demonstrated. The production of *OH was induced by incubating the fungus with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-EDTA. Under these conditions, *OH were generated through DBQ redox cycling catalyzed by quinone reductase and laccase. The capability of T. versicolor growing in malt extract medium to produce *OH by this mechanism was shown during primary and secondary metabolism, and was quantitatively modulated by the replacement of EDTA by oxalate and Mn2+ addition to DBQ incubations. Oxidation of BTEX was observed only under *OH induction conditions. *OH involvement was inferred from the high correlation observed between the rates at which they were produced under different DBQ redox cycling conditions and those of benzene removal, and the production of phenol as a typical hydroxylation product of *OH attack on benzene. All the BTEX compounds (500 microM) were oxidized at a similar rate, reaching an average of 71% degradation in 6 h samples. After this time oxidation stopped due to O2 depletion in the closed vials used in the incubations.
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PMID:Advanced oxidation of benzene, toluene, ethylbenzene and xylene isomers (BTEX) by Trametes versicolor. 2062 9

Plant consortium-AG of Aster amellus Linn. and Glandularia pulchella (Sweet) Tronc. showed complete decolorization of a dye Remazol Orange 3R in 36 h, while individually A. amellus and G. pulchella took 72 and 96 h respectively. Individually A. amellus showed induction in the activities of enzymes veratryl alcohol oxidase and DCIP reductase after degradation of the dye while G. pulchella showed induction of laccase and tyrosinase, indicating their involvement in the dye metabolism. Consortium-AG showed induction in the activities of lignin peroxidase, veratryl alcohol oxidase, laccase, tyrosinase and DCIP reductase. Two different sets of induced enzymes from A. amellus and G. pulchella work together in consortium-AG resulting in faster degradation of the dye. The degradation of the dye into different metabolites was confirmed using High Performance Liquid Chromatography and Fourier Transform Infra Red Spectroscopy. Gas Chromatography Mass Spectroscopy analysis identified four metabolites of dye degradation by A. amellus as acetamide, benzene, naphthalene and 3-diazenylnaphthalene-2-sulfonic acid, four metabolites by G. pulchella as acetamide, 3-diazenyl-4-hydroxynaphthalene-2-sulfonic acid, naphthalen-1-ol and (ethylsulfonyl)benzene, while two metabolites by consortium-AG as 2-(phenylsulfonyl)ethanol and N-(naphthalen-2-yl)acetamide. The non-toxic nature of the metabolites of Remazol Orange 3R degradation was revealed by phytotoxicity studies.
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PMID:Differential fate of metabolism of a sulfonated azo dye Remazol Orange 3R by plants Aster amellus Linn., Glandularia pulchella (Sweet) Tronc. and their consortium. 2149 98

This study investigated the feasibility of a two-step process for the removal of benzene from buffered synthetic wastewater. Benzene is outside the scope of enzymatic removal. In order to remove it from wastewater using enzyme, its pretreatment by modified Fenton reaction was employed to generate the corresponding phenolic compounds. In the first phase, the optimum pH, H2O2 and Fe2+ concentrations and reaction time for the Fenton reaction were determined to maximize the conversion of benzene to phenolic compounds without causing significant mineralization. The pretreatment process was followed by oxidative polymerization of the phenolic compounds catalyzed by a laccase from Trametes villosa. Factors of interest for the three-hour enzymatic treatment were pH and laccase concentration. Under optimum Fenton reaction conditions, 80% conversion of the initial benzene concentration was achieved, giving a mixture containing oxidative dimerization product (biphenyl) and hydroxylation products (phenol, catechol, resorcinol, benzoquinone and hydroquinone). Enzymatic removal of biphenyl and benzoquinone was not possible but 2.5 U/mL laccase was successful in removal of the rest of the phenolic
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PMID:Removal of benzene from wastewater via Fenton pre-treatment followed by enzyme catalyzed polymerization. 2186 66

The aim of this study was to examine the ability of an extracellular fungal laccase (LAC) to form colored products from simple non-colored organic precursors. Thirty different phenolic and non-phenolic precursors (o-, m-, and p-methoxy-, hydroxy-, sulfonic-, and amino-substituted) were tested as single and coupled substrates in a LAC-catalyzed oxidation. The findings show that LAC catalyzes the formation of colored products (from yellow/brown to red and blue) by oxidation of single substrates that are benzene derivatives containing at least two substituents comprised of amino, hydroxy, and methoxy groups. All precursors were tested by cyclic voltammetry and the correlation between their structure and redox potential, and the possibility of their transformation into colored products by fungal LAC was found. Colored products were yielded from single substrates possessing a value of the oxidation peak (E(o)) lower than 1,150 mV vs. normal hydrogen electrode (NHE). Substrates with an oxidation peak higher than 1,150 mV vs. NHE were transformed by LAC into colored compounds only in the presence of an additional precursor characterized by a low value of E(o) and the presence of reactive substituents such as methoxy, hydroxy, and amino groups. Therefore, additional hydroxylation, methoxylation, and amination of phenolic and non-phenolic substrates may represent a strategy to increase the range of these compounds as potential dyes precursors.
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PMID:Structure/redox potential relationship of simple organic compounds as potential precursors of dyes for laccase-mediated transformation. 2199 Feb 79

Chlorinated compounds constitute an important class of xenobiotics. Crude laccase was produced using Trametes versicolor ATCC (200801) in potato dextrose broth, with wheat bran as an inducing medium, and its ability to dechlorinate eight compounds was determined. The compounds were 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, heptachlor and pentachlorophenol. A range of parameters for the dechlorination of some compounds was tested, including incubation period, pH, initial substrate concentration, temperature, and enzyme quantity. The oxygen consumption was determined during each dechlorination process, under pre-determined optimum conditions. The changes in chemical structure of the compounds were also determined, by using FTIR analysis, following dechlorination of test chlorophenolics. Strong interactions were found to lead to the reactivity of hydroxyl groups in some cases and chlorine atoms were released from the benzene ring. The changes in compound toxicity were monitored before and after enzymatic treatment, using Microtox. Quantitative structure-activity relationships for the toxicity of the chlorinated compounds were developed. Consequently, the toxic activity of the test compounds was controlled by electrophilic index and electronic properties.
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PMID:Dechlorination of chlorinated compounds by Trametes versicolor ATCC 200801 crude laccase and quantitative structure-activity relationship of toxicity. 2275 41


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