@prefix prodottidellaricerca: . @prefix istituto: . @prefix prodotto: . istituto:CDS053 prodottidellaricerca:prodotto prodotto:ID33334 . @prefix pubblicazioni: . @prefix unitaDiPersonaleEsterno: . unitaDiPersonaleEsterno:ID6254 pubblicazioni:autoreCNRDi prodotto:ID33334 . unitaDiPersonaleEsterno:ID6253 pubblicazioni:autoreCNRDi prodotto:ID33334 . @prefix modulo: . modulo:ID2556 prodottidellaricerca:prodotto prodotto:ID33334 . unitaDiPersonaleEsterno:ID8075 pubblicazioni:autoreCNRDi prodotto:ID33334 . @prefix rdf: . prodotto:ID33334 rdf:type prodotto:TIPO1101 . @prefix retescientifica: . prodotto:ID33334 rdf:type retescientifica:ProdottoDellaRicerca . @prefix rdfs: . prodotto:ID33334 rdfs:label "An Assessment of the Realative Contributions of Redoc and Steric Issue to Laccase Specificit\u00E0 Towards Substrates (Articolo in rivista)"@en . @prefix xsd: . prodotto:ID33334 pubblicazioni:anno "2008-01-01T00:00:00+01:00"^^xsd:gYear ; pubblicazioni:doi "10.1039/b716002j"^^xsd:string . @prefix skos: . prodotto:ID33334 skos:altLabel "
Aweke Tadesse M.; D'\u0092Annibale A.; Galli C.; Gentili P.; Sergi F. (2008)
An Assessment of the Realative Contributions of Redoc and Steric Issue to Laccase Specificit\u00E0 Towards Substrates
in Organic & biomolecular chemistry
"^^rdf:HTML ; pubblicazioni:autori "Aweke Tadesse M.; D'\u0092Annibale A.; Galli C.; Gentili P.; Sergi F."^^xsd:string ; pubblicazioni:paginaInizio "868"^^xsd:string ; pubblicazioni:paginaFine "878"^^xsd:string ; pubblicazioni:numeroVolume "6"^^xsd:string . @prefix ns11: . prodotto:ID33334 pubblicazioni:rivista ns11:ID74904 ; skos:note "ISI Web of Science (WOS)"^^xsd:string ; pubblicazioni:affiliazioni "Dipartimento diChimica, Universit`a 'La Sapienza', and IMC-CNR Sezione\nMeccanismi di Reazione"^^xsd:string ; pubblicazioni:titolo "An Assessment of the Realative Contributions of Redoc and Steric Issue to Laccase Specificit\u00E0 Towards Substrates"^^xsd:string ; prodottidellaricerca:abstract "Laccases catalyze the one-electron oxidation of a broad range of substrates coupled to the 4 electron\nreduction of O2 to H2O. Phenols are typical substrates, because their redox potentials (ranging from 0.5\nto 1.0 V vs. NHE) are low enough to allow electron abstraction by the T1 Cu(II) that, although a\nrelatively modest oxidant (in the 0.4-0.8 V range), is the electron-acceptor in laccases. The present study\ncomparatively investigated the oxidation performances of Trametes villosa and Myceliophthora\nthermophila laccases, two enzymes markedly differing in redox potential (0.79 and 0.46 V). The\noxidation efficiency and kinetic constants of laccase-catalyzed conversion of putative substrates were\ndetermined. Hammett plots related to the oxidation of substituted phenols by the two laccases, in\ncombination with the kinetic isotope effect determination, confirmed a rate-determining electron\ntransfer from the substrate to the enzyme. The efficiency of oxidation was found to increase with the\ndecrease in redox potential of the substrates, and theMarcus reorganisation energy for electron transfer\nto the T1 copper site was determined. Steric hindrance to substrate docking was inferred because some\nof the phenols and anilines investigated, despite possessing a redox potential compatible with\none-electron abstraction, were scarcely oxidised. A threshold value of steric hindrance of the substrate,\nallowed for fitting into the active site of T. villosa laccase, was extrapolated from structural information\nprovided by X-ray analysis of T. versicolor lac3B, sharing an identity of 99% at the protein level, thus\nenabling us to assess the relative contribution of steric and redox properties of a substrate in\ndetermining its susceptibility to laccase oxidation. The inferred structural threshold is compatible with\nthe distance between two phenylalanine residues that mark the entrance to the active site. Interaction of\nthe substrate with other residues of the active site is commented on." ; prodottidellaricerca:prodottoDi modulo:ID2556 , istituto:CDS053 ; pubblicazioni:autoreCNR unitaDiPersonaleEsterno:ID8075 , unitaDiPersonaleEsterno:ID6254 , unitaDiPersonaleEsterno:ID6253 . ns11:ID74904 pubblicazioni:rivistaDi prodotto:ID33334 .