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At least 937 records · Page 52Linked to original sources
PubMed1999

Molecular cloning of aryl-alcohol oxidase from the fungus Pleurotus eryngii, an enzyme involved in lignin degradation.

Aryl-alcohol oxidase (AAO), an extracellular enzyme characteristic of fungi from the genus Pleurotus, constitutes a source for H2O2 required in lignin biodegradation. The gene aao has been cloned, sequenced and characterized for the first time in Pleurotus eryngii. Both cDNA and genomic libraries were screened with probes obtained by PCR using as primers oligonucleotides corresponding to the N-terminus and internal sequences of AAO. DNA sequences from positive clones showed a unique open reading frame of 1779 nucleotides interrupted by 12 introns. The conceptual translation of the protein agrees with the partial amino acid sequences obtained from protein sequencing. A search for proteins with related amino-acid sequences revealed that glucose oxidase from Aspergillus niger has 33% identity and 51% similarity. A comparison with other oxidoreductases showed common motifs in both N- and C-terminal regions corresponding, respectively, to the FAD-binding region and the enzyme active site. However, AAO probably has structural differences with other oxidases, as deduced from its unique ability to generate H2O2 from the oxidation of aromatic alcohols.

Alcohol Oxidoreductases↗
PubMedDate not supplied

[Enzymes of white rot fungi involved in lignin degradation].

The presence of oxidases and peroxidases was tested qualitatively in 12 strains of white rot Basidiomycetes. Plate tests with gallic acid, tannic acid, guayacol, Poly R-478 and Azure B were used. Fomes sclerodermeus, Phlebia sp. and Pycnoporus sanguineus were selected for further studies because they produced the largest areas of degradation in all media tested. Poly R-478 degradation and manganese peroxidase, lignin peroxidase and laccase activities were measured in glucose-asparagine (N-sufficient) and Kirk (N-limited) media. The highest activities were produced by F. sclerodermeus cultured in glucose asparagine medium.

Culture Media↗
PubMedDate not supplied

[Modification of wood lignin by the fungus Panus tigrinus].

The treatment of sawdust with the fungus Panus tigrinus VKM F-3616 D changed the contents of functional groups in lignin from wood raw material. These changes are accompanied by the release of carboxyl and phenyl hydroxyl groups involved in chemical bond formation between wood particles in pressed materials manufactured from wood wastes.

Basidiomycota↗
PubMed2000

[Measurement for relative molecular mass distribution of lignin dispersants].

Gel chromatography was employed to measure relative molecular mass distribution of lignin dispersants. The results show that relative molecular mass distribution of Reax-85A(I) and M-9(II) are respectively to be from 500 to 35,000 and from 1,000 to 50,000. The fractions separated from (I) and (II) by thin layer chromatography were also investigated through gel chromatography to prove that these fractions were mainly separated depending on relative molecular mass.

Chromatography, Gel↗
PubMedDate not supplied

Anti-influenza virus activity of a lignin fraction from cone of Pinus parviflora Sieb. et Zucc.

When mice were inoculated intranasally or intracerebrally with lethal doses of influenza virus A/WSN/33, most died within 12 days. However, the infectivity of virus that had been preincubated with a lignin prepared from cones of Pinus parviflora Sieb. et Zucc. (PC-Fr. VI) was significantly reduced. Intraperitoneal or oral administration of PC-Fr. VI, prior to virus inoculation, slightly increased the survival ratio of the infected mice. Experiments using radiolabeled PC-Fr. VI revealed that this fraction effectively binds to virions as well as to cultured cells. These data suggest that PC-Fr. VI either inactivates the virus or induces the anti-viral state in cells by binding to virions or cells.

Administration, Oral↗
PubMed2005

Adsorption/desorption behavior between a novel amphoteric granular lignin adsorbent and reactive red K-3B in aqueous solutions.

A novel amphoteric granular lignin adsorbent (AGLA) was prepared using magnesium lignosulfonate as a raw material which was provided by a straw sulfite pulp mill in Guangdong Province, China. A reactive dye (red K-3B) was used as an adsorbate to investigate the adsorption behavior by static and mobile ways. The removal of reactive red K-3B was found to be initially pH and concentration dependent. Moreover, an increase of solution temperature ranging from 5 degrees C to 60 degrees C helped to enhance the rate of intraparticle diffusion of adsorbate and changes in the size of the pores of the adsorbent and thus to reduce the adsorption time. The total breakthrough adsorption capacity was 531 mg/g, and the saturated adsorption capacity was 560 mg/g, which prevailed over the activated carbons evidently. The reactive red K-3B adsorbed on AGLA could be recovered with a mixture of alcohol, NaCl and HCl aqueous solutions. The recovery percentage could reach 92.4%.

Adsorption↗
PubMed1991

Reactions of lignin peroxidase compounds I and II with veratryl alcohol. Transient-state kinetic characterization.

Stopped-flow techniques were utilized to investigate the kinetics of the reaction of lignin peroxidase compounds I and II (LiPI and LiPII) with veratryl alcohol (VA). All rate data were collected from single turnover experiments under pseudo first-order conditions. The reaction of LiPI with VA strictly obeys second-order kinetics over the pH range 2.72-5.25 as demonstrated by linear plots of the pseudo first-order rate constants versus concentrations of VA. The second-order rate constants are strongly dependent on pH and range from 2.62 x 10(6) M-1 s-1 (pH 2.72) to 1.45 x 10(4) M-1 s-1 (pH 5.25). The reaction of LiPII and VA exhibits saturation behavior when the observed pseudo first-order rate constants are plotted against VA concentrations. The saturation phenomenon is quantitatively explained by the formation of a 1:1 LiPII-substrate complex. Results of kinetic and rapid scan spectral analyses exclude the formation of a LiPII-VA cation radical complex. The first-order dissociation rate constant and the equilibrium dissociation constant for the LiPII reaction are also pH dependent. Binding of VA to LiPII is controlled by a heme-linked ionizable group of pKa approximately 4.2. The pH profiles of the second-order rate constants for the LiPI reaction and of the first-order dissociation constants for the LiPII reaction both demonstrate two pKa values at approximately 3.0 and approximately 4.2. Protonated oxidized enzyme intermediates are most active, suggesting that only electron transfer, not proton uptake from the reducing substrate, occurs at the enzyme active site. These results are consistent with the one-electron oxidation of VA to an aryl cation radical by LiPI and LiPII.

Basidiomycota↗
PubMedDate not supplied

Antimicrobial spectrum of lignin-related pine cone extracts of Pinus parviflora Sieb. et Zucc.

Pine cones of Pinus parviflora Sieb., et Zucc, were extracted successively with 5% NaHCO3, 3% NH4OH, 1% NaOH and 4% NaOH, and the extracts were tested for ability to induce antimicrobial activity in mice infected with Staphylococcal aureus. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, or Salmonella enteritidis. These alkaline extracts were potent against the first 5 of these strains of microorganisms, and the activity was recovered mostly from their acid-precipitates at pH 5. After further fractionation on a Sephadex LH-60 column, the highest molecular weight fraction was most potent. Chemical structures in these bioactive fractions were assumed to be lignin-related structures, based on spectral data from UV, NMR and IR spectroscopy.

Anti-Bacterial Agents↗
PubMed1990

[O-demethylation and metabolism of the methoxyl group of vanillic acid, monomer model of lignin, by the rumen bacterium Syntrophococcus sucromutans].

The O-demethylation of a lignin monomer by washed cells of the rumen bacterium S sucromutans was studied using chemically synthesized O-[methyl-14C]vanillate. During cometabolism of pyruvate and vanillate, the label from the methoxyl group was incorporated into acetate, the sole product, which was singly labeled in the methyl group.

Animals↗
PubMedDate not supplied

Induction of antiparasite activity by pine cone lignin-related substances.

Pretreatment with two distinct lignin-related antitumor substances extracted from pine cone of Pinus parviflora Sieb. et Zucc. protected infant mice from Hymenolepis nana (Cestoda) infection. Subcutaneous administration of these fractions (10 mg/kg) to 1 week old mice evoked strong protective immunity against oral infection by Hymenolepis nana eggs. Significant antiparasite effects were also induced in 4 week old mice by intraperitoneal or oral administration of these fractions. These fractions had more potent antiparasite activity than pine cone extracts with lower antitumor and antiviral activity, and various polysaccharides derived from plants and bacteria.

Animals↗
PubMed1988

Biochemical and genetic studies of bacteria metabolizing lignin-related compounds.

The ability of bacterial strains to metabolize lignin model compounds was studied. Strains examined were non-filamentous bacterial isolates obtained from decaying wood and the actinomycete Streptomyces viridosporus T7A. Model compounds included dimers containing either the beta-1 (1,2-diarylethane) or the beta-O-4 (arylglycerol-beta-aryl ether) type of linkage. Pseudomonas fluorescens biovar I A1 proliferated on anisoin (4,4'-dimethoxybenzoin) accumulating anisic acid temporarily. Cleavage at the beta-1 bond was also observed with crude extracts prepared from the same strain. In turn, cleavage of the beta-O-4 linkage of veratrylglycerol-beta-guaiacyl ether was detected in cultures of Pseudomonas acidovorans D3. In this case, main degradation intermediates were beta-hydroxypropioveratrone, acetoveratrone and guaiacol. S. viridosporus T7A reduced the carbonyl group of some beta-1 dimers and did not modify the beta-O-4 model compounds tested. Attempts to ascribe a catabolic character to large molecular weight extrachromosomal DNA present in some strains were unsuccessful. Gene banks of P. fluorescens biovar I A1 and P. acidovorans D3 were prepared utilizing the broad host range cosmid pLAFR1 as vector.

Bacteria↗
PubMed1982

Enzymic synthesis of lignin precursors. Purification and properties of 4-coumarate:CoA ligase from cambial sap of spruce (Picea abies L.).

4-Coumarate:CoA ligase was purified from cambial sap of spruce (Picea abies). A 1627-fold purification of the enzyme with a yield of 37% was achieved by a six-step procedure including dye-ligand chromatography. Isozymes of the ligase were not detected. The enzyme has an Mr of about 63 000 and is a single polypeptide chain. Ferulic, 4-coumaric and caffeic acids are efficient substrates for the ligase. In contrast to some ligases from angiosperms, the ligase from spruce (gymnosperm) does not activate sinapic acid. The substrate specificity of the ligase is consistent with the lignin composition of spruce.

Coenzyme A Ligases↗
PubMed1994

Domain structure of laccase I from the lignin-degrading basidiomycete PM1 revealed by differential scanning calorimetry.

The application of scanning calorimetry to investigate laccase I from the lignin-degrading basidomycete PM1 (CECT 2971) showed three thermal transitions beneath the overall endotherm following the previous heating of the sample up to 60 degrees C. The thermodynamic parameters of these three transitions satisfy a model of two-state independent unfolding, supporting a three-domain organization of the enzyme. It is shown that the catalytic site of laccase I is located in the domain with the thermally-induced transition at 76 degrees C.

Amino Acid Sequence↗
PubMed1995

[Biologically active lignins from Magnolia biondii Pamp].

Guided by PAF induced platelet aggregation, six active lignins were isolated from the flower buds of Magnolia biondii and identified as fargesin, demethoxyaschantin, aschantin, pinoresinol dimethyl ether, magnolin, lirioresinol-B dimethyl ether. The 13CNMR and CD data were reported and the configurations were determined.

Drugs, Chinese Herbal↗
PubMedDate not supplied

[Study of oxidative enzymes of the lignin-degrading fungus Pleurotus ostreatus].

The elctrophoretic separation in polyacrylamide gel of laccase and peroxidase isoenzymes of the lignin-degrading fungus Pleurotus ostreatus was investigated. The optimal electrophoretic conditions were found: in the electrode buffer tris-diethyl barbituric acid pH 7.0 in the gradient gel-4-10% acrylamide. Seven peroxidase isoenzymes oxidizing base benzidine and guaiacol were identified and five laccase isoenzymes reacting with specific substrates-p-phenylene diamine, alphs-naphthol, pyrogallol, hydroquinone were determined.

Agaricales↗
PubMedDate not supplied

Induction of DNA fragmentation by tannin- and lignin-related substances.

A variety of tannin and lignin-related compounds were compared for their ability to induce nucleosome-sized DNA fragmentation (a biochemical hallmark of apoptosis), using agarose gel electrophoresis and a fluorescence activated cell sorter. Monomeric, dimeric, trimeric and tetrameric hydrolysable tannins induced nucleosome-sized DNA fragmentation in HL-60 cells, more potently than condensed tannins. The highest activity was detected in gallic acid, a component unit of tannins. Natural lignified materials, except for caffeic acid and its dehydrogenation polymer, showed much weaker activity. Protein-bound polysaccharide (PSK) was inactive. Gallic acid induced DNA fragmentation in four human myelogenous leukaemic cell lines, but not in human T-cell leukaemia and erythroleukaemia cell lines. Ca2+ depletion from the culture medium slightly, but significantly, reduced the apoptosis-inducing activity of gallic acid, but did not significantly affect that of tannic acid or caffeic acid. After treatment with gallic acid, intracellular Ca2+ concentration was significantly elevated. The apoptosis-inducing activity of polyphenols may further emphasize their medicinal efficacy.

Apoptosis↗
PubMed2004

Activation of lignin peroxidase in organic media by reversed micelles.

Activation of lignin peroxidase (LIP) in an organic solvent by reversed micelles was investigated. Bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) was used as a surfactant to form a reversed micelle. Lyophilized LIP from an optimized aqueous solution exhibited no enzymatic activity in any organic solvents examined in this study; however, LIP was catalytically active by being entrapped in the AOT reversed micellar solution. LIP activity in the reversed micelle was enhanced by optimizing either the preparation or the operation conditions, such as water content and pH in water pools of the reversed micelle and the reaction temperature. Stable activity was obtained in isooctane because of the stability of the reversed micelle. The optimal pH was 5 in the reversed micellar system, which shifted from pH 3 in the aqueous solution. The degradation reaction of several environmental pollutants was attempted using LIP hosted in the AOT reversed micelle. Degradation achieved after a 1-h reaction reached 81%, 50%, and 22% for p-nonylphenol, bisphenol A, and 2,4-dichlorophenol, respectively. This is the first report on the utilization of LIP in organic media.

Colloids↗