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)

In the present study we investigated the possibility of proteinases, intracellular and extracellular, being involved in the regulation of ligninolytic activities in cultures of Trametes versicolor during the shift from primary growth (i.e. trophophase) to idiophase triggered by nitrogen or carbon starvation. These studies were performed using specific inhibitors added to the cultures of T. versicolor. Addition of PMSF (irreversible inhibitor of serine proteinases) or chloroquine (the lysosomotropic agent inhibiting intralysosomal degradation of proteins) revealed distinct differences in the activity of ligninolytic enzymes between nutrient-deprived and non-starved cultures. The addition of PMSF during the transfer of mycelia to the nutrient limited media significantly enhanced the activities of laccase (2-7-fold) and of unspecified peroxidases (2-4-fold). The activity of lignin peroxidase decreased with PMSF, both in tropho- and in idiophasic cultures. The enhanced activities of laccase and general peroxidases (horseradish peroxidase-like, HRP-like) were accompanied by markedly altered patterns of both intracellular and extracellular proteolytic activities revealed by electrophoretic analysis with polyacrylamide gels containing the copolymerized substrate (haemoglobin or gelatin, respectively). The experiments with chloroquine added to nutrient-deprived cultures showed that inhibition of vacuolar proteolysis resulted in lowered activities of laccase and peroxidase. Electrophoretic analysis revealed altered patterns of intracellular proteinases upon chloroquine addition to nutrient-starved cultures. Moreover, chloroquine was found to enhance the activity of proteases secreted in carbon-starved cultures. From the results it is concluded that both intracellular (including vacuolar) and extracellular proteases are involved in the regulation of laccase and peroxidase activity in cultures of T. versicolor under nutrient limitation.
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PMID:Studies on the role of proteases in the white-rot fungus Trametes versicolor: effect of PMSF and chloroquine on ligninolytic enzymes activity. 1074 99

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.
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PMID:[Enzymes of white rot fungi involved in lignin degradation]. 1088 8

Growth parameters, ligninolytic enzyme activities and ability to degrade polycyclic aromatic hydrocarbons by the fungus Irpex lacteus were characterized and compared with those of other white rot fungi capable of rapid decolorization of poly R-478 and Remazol Brilliant Blue R dyes. I. lacteus was able to grow on mineral and complex media and efficiently colonized sterile and non-sterile soil by exploratory mycelium growing from a wheat straw inoculum. In shallow stationary cultures growing on high nitrogen mineral medium containing 45 mM ammonium as nitrogen source, the fungus produced lignin peroxidase (LIP), Mn-dependent peroxidase (MnP) and laccase simultaneously, the respective maximal activities of 70, 970 and 36 U/l being attained around day 18. Growing in nitrogen-limited medium (2.4 mM ammonium), no LIP was formed and levels of MnP and laccase decreased significantly. During growth in sterile soil, the fungus synthesized LIP and laccase but not MnP. I. lacteus efficiently removed three- and four-ringed PAHs from liquid media and artificially spiked soil. The variety of ligninolytic enzymes, robust growth, capability of soil colonization and resistance to inhibitory action of soil bacteria make I. lacteus a suitable fungal organism for use in bioremediation.
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PMID:Irpex lacteus, a white rot fungus applicable to water and soil bioremediation. 1115 80

White rot fungi produce three main extracellular enzymes involved in ligninolysis; laccase, lignin peroxidase and manganese peroxidase. Though all white rot fungi do not produce all three enzymes, laccase occupies an important place in ligninolysis. The present paper reports its production by some white rot fungi; Daedalea flavida, Phlebia brevispora, Phlebia radiata and Polyporus sanguineus under different nutritional conditions. Of the various basal media tested, mineral salts malt extract broth proved to be the best medium for laccase production. Sugarcane bagasse proved to be the best laccase inducer among the various supplements added to different media.
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PMID:Effects of various media and supplements on laccase production by some white rot fungi. 1121 Oct 81

Efficacy of a white rot fungus G. lucidum for reduction of colour of paper mill effluent under various growth conditions was evaluated. G. lucidum cultured in IBME medium supported maximum colour reduction on 18th day of fungal growth. The optimization of growth parameters further improved colour reduction. The 18 day old culture at 4 g/l inoculum concentration resulted in maximum decolourization (89%) of the effluent with pH adjusted to 6.5 at 35 degrees C along with maximum reduction in biological oxygen demand and chemical oxygen demand. Relative contribution of lignin peroxidase and laccase to the decolourization of paper mill effluent by G. lucidum was also observed.
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PMID:Influence of culture parameters on paper mill effluent decolourization by a white rot fungus Ganoderma lucidum. 1121 17

Ten strains belonging to five species of European Armillaria (Fr.:Fr.) Staude were examined for their ability to produce laccase, lignin peroxidase, manganese-dependent peroxidase and manganese-independent peroxidase. No lignin peroxidase activity was observed in any of the strains. Manganese-dependent peroxidase production by all tested strains was low. Difference in the ratio of laccase to manganese-independent peroxidase in strains of A. gallica in comparison to all other species was detected.
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PMID:Ligninolytic enzyme complex of Armillaria spp. 1127 9

The major products of the initial steps of ferulic acid polymerization by lignin peroxidase included three dehydrodimers resulting from beta-5' and beta-beta'coupling and two trimers resulting from the addition of ferulic acid moieties to decarboxylated derivatives of beta-O-4'- and beta-5'-coupled dehydrodimers. This is the first time that trimers have been identified from peroxidase-catalyzed oxidation of ferulic acid, and their formation appears to be favored by decarboxylation of dehydrodimer intermediates. After initial oxidation, the coupling reactions appear to be determined by the chemistry of ferulic acid phenoxy radicals, regardless of the enzyme and of whether the reaction is performed in vitro or in vivo. This claim is supported by our finding that horseradish peroxidase provides a similar product profile. Furthermore, two of the dehydrodimers were the two products obtained from laccase-catalyzed oxidation (Tatsumi, K. S., Freyer, A., Minard, R. D., and Bollag, J.-M. (1994) Environ. Sci. Technol. 28, 210-215), and the most abundant dehydrodimer is the most prominent in grass cell walls (Ralph, J., Quideau, S., Grabber, J. H., and Hatfield, R. D. (1994) J. Chem. Soc. Perkin Trans. 1, 3485-3498). Our results also indicate that the dehydrodimers and trimers are further oxidized by lignin peroxidase, suggesting that they are only intermediates in the polymerization of ferulic acid. The extent of polymerization appears to be dependent on the ionization potential of formed intermediates, H(2)O(2) concentration, and, probably, enzyme stability.
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PMID:Initial steps of ferulic acid polymerization by lignin peroxidase. 1127 69

A cell suspension culture of a tobacco (Nicotiana tabacum L. cv. Petit Havana) cell line derived from a cultivar transformed with the Tcyt gene from Agrobacterium, which leads to high endogenous levels of cytokinin, has been established. This cell line shows increased cell aggregation, elongated cells and a 5-fold increase in wall thickness. If allowed to carry on growing it can form a single mass without shedding cells into the medium. When analysed at an earlier growth stage, these cultures were found to produce improved levels of vascular nodule formation than in other systems that employ exogenous cytokinin. This differentiation was optimised with respect to sucrose and auxin signals in order to induce maximum production of cells with thickened walls and a morphology characteristic of fibre cells and tracheids, in addition to cells that remain meristematic. In order to establish the validity of this system for studying secondary wall formation, the walls and associated biosynthetic changes were analysed in these cells by chemical analysis of the walls, changes in activities of enzymes of xylan and monolignol synthesis, and expression of mRNAs coding for enzymes of lignin biosynthesis. The wall composition of the transformed cells was compared with that determined for primary walls from a typical untransformed tobacco cell line. Recovery of wall material was 50% greater in the transformed culture. In this material a major difference was found in the pectin fraction where there was a distinct difference in size distribution together with a lower level of methylation for the transformed line, which may be related to increased adhesiveness. There were increased amounts of xylan, although the ratio of xyloglucan to xylan content was not substantially different due to the mixture of cell types. There was also an increase in cellulose and phenolic components. Increased activity of enzymes involved in the synthesis of xylan as a marker for the secondary wall occurred around the time of tracheid differentiation and coincided with a broad peak of cinnamyl alcohol dehydrogenase activity. The expression of mRNAs coding for enzymes of the general phenylpropanoid pathway, phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, catechol O-methyl transferase was relatively constitutive in the cultures while transcripts of ferulate 5-hydroxylase, cinnamoyl CoA-reductase, cinnamyl alcohol dehydrogenase and lignin peroxidase were induced. The walls of the transformed cells also showed considerable differences in the subset of extractable proteins from that found in primary walls of tobacco when these were subjected to proteomic analysis. Many of these proteins appear to be novel and not present in primary walls. However an Mr-32,000 chitinase, an Mr-34,000 peroxidase, an Mr-65,000 polyphenoloxidase/laccase and possibly an Mr-68,000 xylanase could be identified as well as structural proteins.
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PMID:Proteomic analysis reveals a novel set of cell wall proteins in a transformed tobacco cell culture that synthesises secondary walls as determined by biochemical and morphological parameters. 1128 5

Dichomitus squalens belongs to a group of white-rot fungi which express manganese peroxidase (MnP) and laccase but do not express lignin peroxidase (LiP). To facilitate structure/function studies of MnP from D. squalens, we heterologously expressed the enzyme in the well-studied basidiomycete, Phanerochaete chrysosporium. The glyceraldehyde-3-phosphate-dehydrogenase (gpd) promoter of P. chrysosporium was fused to the coding region of the mnp2 gene of D. squalens, 5 bp upstream of the translation start site, and placed in a vector containing the ural gene as a selectable marker. Purified recombinant protein (rDsMnP) was similar in kinetic and spectral characteristics to both the wild-type MnPs from D. squalens and P. chrysosporium (PcMnP). The N-terminal amino acid sequence of the rDsMnP was determined and was identical to the predicted sequence. Cleavage of the propeptide followed a conserved amino acid motif (A-A-P-S/T) in both rDsMnP and PcMnP. However, the protein from D. squalens was considerably more thermostable than its P. chrysosporium homolog with half-lives 15- to 40-fold longer at 55 degrees C. As previously demonstrated for PcMnP, addition of exogenous MnII and CdII conferred additional thermal stability to rDsMnP. However, unlike PcMnP, ZnII also confers some additional thermal stability to rDsMnP at 55 degrees C. Some differences in the metal-specific effects on thermal stability of rDsMnP at 65 degrees C were noted.
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PMID:Heterologous expression of athermostable manganese peroxidase from Dichomitus squalens in Phanerochaete chrysosporium. 1136 16

Low molecular-weight compounds, structurally related to lignin, increase the production of laccase, lignin peroxidase, manganese dependent peroxidase, and feed-back type enzymes such as glucose oxidase, cellobioso-quinone oxidoreductase, and glyoxal oxidase in the culture of the white rot fungus Phlebia radiata growing on different carbon sources.
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PMID:Production of lignolytic and feed-back type enzymes by Phlebia radiata on different media. 1139 34


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