1,721,016 research outputs found
Aromatic ring cleavage of veratryl alcohol by crude extracts and by purified manganese dependent peroxidase from Lentinus edodes
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Kinetic behaviour and degradative capability of Lentinula edodes laccase isoenzymes with differently substituted chlorinated substrates
No full textPartially purified Lentinula edodes laccase was tested for its ability to oxidize several putative mono-, di- and tri-chlorinated substrates. Both the initial reaction rate and removal efficiency were remarkably affected by the nature of substituents and their position on the aromatic ring. Chlorinated phenols and/or anilines bearing an additional substituent with at least one lone pair electrons adjacent to the benzene ring were preferentially oxidized by the enzyme. In contrast, chlorinated substrates bearing an electron-withdrawing substituent, such as the nitro group, were not oxidized at all. The extent of removal of the most reactive chlorinated compounds after 1 h incubation with laccase was in the following order: chlorohydroquinone > 4,6-dichlororesorcinol > 2-amino-4-chlorophenol > 2,6-dichlorophenol > 2,4-dichlorophenol > 2,4,6-trichlorophenol > 2-chlorophenol > 4-chlorophenol
Aqueus plant extracts as stimulators of laccase production in liquid cultures of Lentinus edodes
No full textTotal and specific activities of extra-cellular laccases from Lentinus edodes were enhanced by adding corn straw and chestnut juice to the liquid growth medium. The aqueous extracts were chemically characterized and revealed the presence of several phenolic and non-phenolic compounds. Extensive extraction of these components from the tested extracts completely annulled their stimulating properties on laccase production, suggesting that these compounds can act at micromole levels
Laccase-catalyzed removal of 2,4- dichlorophenol in the presence of polyethylene glycol
No full textThe effect of the additive, polyethylene glycol 4000 (PEG), on the laccase-catalyzed removal of 2,4-dichlorophenol (DCP) from synthetic wastewaters was studied over the DCP concentration range 2-16 mM. Results showed that PEG had a significant protective effect on laccase activity. The amount of enzyme required to obtain 50% pollutant removal was reduced 35-, 39- and 20-fold less than that required without PEG for 4, 8 and 16 mM DCP solutions, respectively
Membrane supported bilayer lipid membranes array: preparation, stability and ion-channel insertion
No full textIn the present paper we describe the preparation and characterization of reconstituted bilayer lipid membranes (BLM) supported on a polycarbonate membrane. BLMs self-assemble on the holes of the membrane, which was previously covered with An and an octadecanethiol (ODT) self-assembled monolayer (SAM). The obtained mixed hybrid bilayer lipid membranes (MHBLM) array allows recording of relatively intense signals. The steps leading to formation of the system have been investigated, its stability determined and reproducibility evaluated. The insertion of an ion channel (Gramicidin D) and a K+ carrier (Valinomycine) was also evaluated. (C) 2002 Elsevier Science B.V. All rights reserved
Mixed hybrid bilayer lipid membrane incorporating valinomycin: improvements in preparation and functioning
No full textThe paper deals with the reconstruction of lipid bilayer membranes on a Au-covered polycarbonate membrane. Such a kind of like-biomembranes (namely mixed hybrid bilayer lipid membrane (MHBLM)) are characterised by appreciable long-term stability. Here we describe changes that have been made in the geometry of the experimental device in order to avoid artefacts and render membrane reproduction easier. Incorporation of valinomycin was performed to check the membrane and its stability: conductance and membrane potential following the changes of ion concentration were recorded. This new approach permits increase of successful trials and renders possible, when it breaks, easily formation of a new MHBLM on the same Au-covered polycarbonate membrane support. Finally, the stability shown by the MHBLM renders this system a promising tool for use under flowing conditions. (C) 2002 Elsevier Science B.V. All rights reserved
Modification of lignin-like compounds in annual plant lignocelluloses and consequences on the paper characteristics
No full textUN APPROCCIO MULTI-FATTORIALE ALLA PRODUZIONE DI PEROSSIDASI FUNGINE E SUCCESSIVA VERIFICA IN FERMENTATORE
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