Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Graphite (GE) or printed graphite electrode (PGE) based biosensors containing recombinant fungal laccase Polyporus pinsitus (rPpL), and Myceliophthora thermophila (rMtL) were developed. The enzymes were immobilized using bovine serum albumin and glutaraldehyde. At pH 5.5 and -0.1 V, the calibration graphs of GE based biosensors were hyperbolic if pyrocatechol was used. The concentration of substrate that results in 50% of steady-state response (EC(50)) was 0.7 mM and sensitivity (S) was 3.8 mA/M. The sensitivity increased up to 4 A/M if larger amount of rPpL was used. The sensitivity of biosensors changed little during 9 days of exploitation, but decreased at longer time. The PGE based biosensors were mounted into the flow-through cell and calibrated under kinetic regime. EC(50) of the biosensors containing rPpL varied from 0.6 to 4.0 mM and sensitivity varied from 0.11 to 1.9 mA/M. The response of biosensor containing thermostable laccase rMtL was less, but response saturated at larger pyrocatechol concentration. The sensitivity changed little during 6 days. Both type of biosensors responded also to 1-naphthol, o-phenylenediamine, guaiacol, o-anizidine, benzidine. The experiments demonstrate recombinant laccases application to biosensor engineering and their use to phenol and related compound determination under steady-state and flow-through regimes.
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PMID:Amperometric biosensors based on recombinant laccases for phenols determination. 1248 79

Twenty-six species of ammonia fungi comprising 71 strains were screened for ligninolytic activity using agar plate tests. The tests comprised a wood powder plate test, the Bavendamm reactions, and a Remazol Brilliant blue R (RBBR) decolorization test. The wood powder plate test detected phenol oxidases of Coprinus spp., whereas this method obviously detected no activities from facultative mycorrhizal fungi, such as Hebeloma radicosoides and ectomycorrhiza: H. spoliatum and H. vinosophyllum. With quantitative assays of ligninolytic activity, Coprinus phlyctidosporus, C. echinosporus, Lyophyllum tylicolor, Lepista nuda, L. tarda, Calocybe leucocephala, and Crucispora rhombisperma, which grow on oak-leaf litter, the major phenol-oxidizing enzyme was a laccase. The concentration of urea affected laccase activity; however, urea was not the obligate nitrogen source for the laccase production.
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PMID:Some characteristics of ammonia fungi 1. In relation to their ligninolytic enzyme activities. 1250 13

Chlorinated phenols are major industrial and agricultural xenobiotics that pollute soil and ground water. It has been shown that laccases catalyze the oxidative coupling of phenolic compounds. Therefore, the transformation of one or a mixture of several chlorinated phenols by a laccase from the fungus Trametes villosa was studied. Generally, if more than one phenol was added, the transformation of chlorinated phenols decreased, and if the concentration of the laccase was increased, the transformation of the phenols was enhanced. There were exceptions to these observations: for instance, the transformation of 0.1 mM 4-chlorophenol incubated with 1 mM 2,4-dichlorophenol in buffered salt solutions was not enhanced if the concentration of the laccase was increased from 2 to 20 DMP units/mL. The reason for the reduced transformation of chlorinated phenols in the presence of additional phenols is still unknown. However, in spite of some limitations, the application of laccase to decontaminate wastewater polluted with chlorinated phenols appears feasible.
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PMID:Enzymatic oxidative transformation of chlorophenol mixtures. 1254 43

A new enzyme has been isolated from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O(2)-dependent oxidation of 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose to tellimagrandin II, the first intermediate in the (4)C(1)-glucose derived series of ellagitannins. CD-spectra revealed that the 4,6-O-HHDP-residue of the in vitro product had the (S)-stereoconfiguration characteristic of tellimagrandin II from natural sources. The enzyme, for which a M(r) of ca. 60,000 was determined, was purified to apparent homogeneity. It had a pH-optimum at pH 5.0, an isoelectric point at pH 6.3 and was most stable at pH 4.2. Inhibition studies suggested that this new enzyme, for which the systematic name 'pentagalloylglucose: O(2) oxidoreductase' is proposed, belongs to the vast group of laccase-type phenol oxidases (EC 1.10.3.2).
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PMID:Oxidation of pentagalloylglucose to the ellagitannin, tellimagrandin II, by a phenol oxidase from Tellima grandiflora leaves. 1262 Mar 41

Grape seeds were used by Trametes hirsuta as a substrate for laccase production giving 23 kU l(-1), which was 10-fold the value attained in the cultures with no lignocellulosic waste addition. The dyes, Indigo Carmine and Bromophenol Blue, were easily decolourised (100% in 24 h) by the extracellular liquid obtained in such cultures, whereas Methyl Orange (65% in 24 h) and Phenol Red (36% in 24 h) were more resistant to degradation. This shows the specificity of laccase towards different dye structures.
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PMID:Grape seeds: the best lignocellulosic waste to produce laccase by solid state cultures of Trametes hirsuta. 1288 77

The sulfonephthalein indicator, phenol red, exhibits an unusually slow rate of oxidation by laccase from Poliporus pinsitus, in spite of the fact that it is a phenol and therefore a natural substrate for this phenoloxidase enzyme. Nevertheless, after prolonged exposure to laccase (24 h) phenol red is oxidized by more than 90%. We found that phenol red, which can be oxidatively converted into a resonance-stabilized phenoxy radical, performs as a mediator in the laccase-catalyzed oxidation of a nonphenolic substrate (4-methoxybenzyl alcohol) and also of a hindered phenol (2,4,6-tri-tert-butylphenol). In particular, phenol red was found to be at least 10 times more efficient than 3-hydroxyanthranilate (a reported natural phenolic mediator of laccase) in the oxidation of 4-methoxybenzyl alcohol. Other phenols, which do not bear structural analogies to phenol red, underwent rapid degradation and did not perform as laccase mediators. On the other hand, several variously substituted sulfonephthaleins, of different pK2 values, mediated the laccase catalysis, the most efficient being dichlorophenol red, which has the lowest pK2 of the series. The mediating efficiency of phenol red and dichlorophenol red was found to be pH dependent, as was their oxidation Ep value (determined by cyclic voltammetry). We argue that the relative abundance of the phenoxy anion, which is easier to oxidize than the protonated phenol, may be one of the factors determining the efficiency of a phenolic mediator, together with its ability to form relatively stable oxidized intermediates that react with the desired substrate before being depleted in undesired routes.
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PMID:First evidence of catalytic mediation by phenolic compounds in the laccase-induced oxidation of lignin models. 1291 28

The transformation by an oxidoreductase (a laccase from Rhus vernificera) of a mixture of four phenols (catechol, methylcatechol, m-tyrosol and hydroxytyrosol) that simulates a typical wastewater derived from an olive oil factory was investigated. Results achieved in this study confirm that laccase-mediated transformation of phenols depends on the nature and the initial concentration of the involved phenol, the time course of the reaction, and mainly, on the complexity of the phenolic incubation mixture. Actually, the four phenols each have a completely different response to enzyme action both in terms of quantitative and kinetic transformation. For example, after 24-h incubation, methylcatechol was completely removed, whereas 30% of untransformed hydroxytyrosol and catechol and more than 65% of m-tyrosol were still present in the reaction mixture. A reduction of enzyme activity occurred for all phenols after enzymatic oxidation. No correspondence between phenol transformation and disappearance of enzymatic activity was observed, thus suggesting that different mechanisms are probably involved in the laccase-mediated transformation of the four phenols. The behavior of phenols became more complex when an increasing number of phenols was present in the reaction mixture, and even more so when different concentrations of phenols were used. Competitive effects may arise when more than one phenol is present in the reaction solution and interacts with the enzyme.
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PMID:Oxidative transformation of phenols in aqueous mixtures. 1450 8

An enzyme has been purified from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O2-dependent oxidation of the monomeric ellagitannin, tellimagrandin II, to a dimeric derivative, cornusiin E. The apparently homogeneous enzyme preparation had a Mr of ca. 160,000 (with four subunits of Mr 40,000), a pH-optimum and an isoelectric point at pH 5.2, and was most stable at pH 4.3. Inhibition studies revealed that this new enzyme, for which the systematic name 'tellimagrandin II: O2 oxidoreductase' is proposed, is a member of the laccase (EC 1.10.3.2) family of phenol oxidases. The properties of this enzyme differed from that of a related laccase that catalyzed the transition of 1,2,3,4,6-pentagalloylglucopyranose to tellimagrandin II, the preceding step in the biosynthetic route to cornusin E.
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PMID:Ellagitannin biosynthesis: laccase-catalyzed dimerization of tellimagrandin II to cornusiin E in Tellima grandiflora. 1459 17

The performance and enzymatic strategy exhibited by basidiomycete Euc-1, a laccase producing strain, was investigated during the biodegradation of olive mill wastewater (OMW). This strain yielded better decolorization of solidified OMW than Phanerochaete chrysosporium and removed 90% of phenols (initial concentration=800 mg l(-1)), 73% of color (initial A465=4.4), and 45% of chemical oxygen demand in batch cultures containing OMW. Since partial phenol removal occurred before the detection of enzymatic activity, no plausible correlation could be established between them. In contrast, decolorization occurred only after the detection of laccase activity and coincided with its production over time. Two laccase fractions (Lac1 and Lac2) were separated by chromatography. OMW strongly induced Lac2 that was almost absent in defined liquid medium. Furthermore, Lac2 was the main laccase fraction in the presence of OMW. This study pointed out that basidiomycete Euc-1 and its ligninolytic system could be a useful tool for the bioremediation of wastewater generated in the process of olive oil extraction.
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PMID:Activity and elution profile of laccase during biological decolorization and dephenolization of olive mill wastewater. 1464 80

An enzyme showing alkaliphilic laccase activity was purified from the culture supernatant of Myrothecium verrucaria 24G-4. The enzyme was highly stable under alkaline conditions, showed an optimum reaction pH of 9.0 for 4-aminoantipyrine/phenol coupling, and decolorized synthetic dyes under alkaline conditions. It showed structural and catalytic similarities with bilirubin oxidase, but preferably oxidized phenolic compounds. The enzyme catalyzed veratryl alcohol oxidation at pH 9.0 with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as a mediator, suggesting that the laccase mediator system functioned well under alkaline conditions.
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PMID:Characterization of alkaliphilic laccase activity in the culture supernatant of Myrothecium verrucaria 24G-4 in comparison with bilirubin oxidase. 1475 42


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