The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. http://http://dspace.unitus.it:80 2013-05-24T11:43:54Z 2013-05-24T11:43:54Z Perazzini, Raffaella Saladino, Raffaele Guazzaroni, Melissa Crestini, Claudia http://hdl.handle.net/2067/1790 2011-06-30T14:23:21Z 2010-12-31T23:00:00Z

Title: A novel and efficient oxidative functionalization of lignin by layer-by-layer immobilised Horseradish peroxidase Authors: Perazzini, Raffaella; Saladino, Raffaele; Guazzaroni, Melissa; Crestini, Claudia Abstract: Horseradish peroxidase (HRP) was chemically immobilised onto alumina particles and coated by polyelectrolytes layers, using the layer-by-layer technique. The reactivity of the immobilised enzyme was studied in the oxidative functionalisation of softwood milled wood and residual kraft lignins and found higher than the free enzyme. In order to investigate the chemical modifications in the lignin structure, quantitative 31P NMR was used. The immobilised HRP showed a higher reactivity with respect to the native enzyme yielding extensive depolymerisation of lignin. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com

2010-12-31T23:00:00Z Cossetti, Cristina Crestini, Claudia Saladino, Raffaele Di Mauro, Ernesto http://hdl.handle.net/2067/1823 2011-06-28T11:55:54Z 2009-12-31T23:00:00Z

Title: Borate minerals and RNA stability Authors: Cossetti, Cristina; Crestini, Claudia; Saladino, Raffaele; Di Mauro, Ernesto Abstract: The abiotic origin of genetic polymers faces two major problems: a prebiotically plausible polymn. mechanism and the maintenance of their polymd. state outside a cellular environment. The stabilizing action of borate on ribose having been reported, the authors have explored the possibility that borate minerals stabilize RNA. Borate itself does not stabilize RNA. The anal. of a large panel of minerals tested in various phys.-chem. conditions shows that in general no protection is exerted on the RNA backbone, with the interesting exception of ludwigite (Mg2Fe3+BO5). Stability is a fundamental property of nucleic polymers and borate is an abundant component of the planet, hence the prebiotic interest of this anal. Description: L'articolo è disponibile sul sito dell'editore: http://www.mdpi.com

2009-12-31T23:00:00Z Saladino, Raffaele Ginnasi, Maria Cristina Collalto, Daniela Bernini, Roberta Crestini, Claudia http://hdl.handle.net/2067/1795 2011-06-29T15:42:40Z 2009-12-31T23:00:00Z

Title: An efficient and selective epoxidation of olefins with novel methyltrioxorhenium/(fluorous ponytailed) 2,2′-bipyridine catalysts Authors: Saladino, Raffaele; Ginnasi, Maria Cristina; Collalto, Daniela; Bernini, Roberta; Crestini, Claudia Abstract: Novel complexes between methyltrioxorhenium (MTO) and bis(fluorous- ponytailed) 2,2′bipyridines (bpy-Fn) were synthesized and used for the oxidation of alkenes with hydrogen peroxide under fluorous catalysis. High conversions and yields of the corresponding epoxides were obtained. Description: L'articolo è disponibile sul sito dell'editore: http://www.onlinelibrary.wiley.com

2009-12-31T23:00:00Z Crestini, Claudia Crucianelli, Marcello Orlandi, Marco Saladino, Raffaele http://hdl.handle.net/2067/1797 2011-06-30T14:38:19Z 2009-12-31T23:00:00Z

Title: Oxidative strategies in lignin chemistry: A new environmental friendly approach for the functionalisation of lignin and lignocellulosic fibers Authors: Crestini, Claudia; Crucianelli, Marcello; Orlandi, Marco; Saladino, Raffaele Abstract: Novel processing methods and product concepts are required to extend the role of lignin for future biomass and biofuel applications in emerging platforms such as the biorefinery. The possible strategies of lignin valorisation are focused into two main directions, namely the selective functionalisation of the lignin polymer or in its oxidative depolymerization to get polyfunctional monomeric compounds. Here we report a panel of biocatalysis, organometallic catalysis, biomimetic catalysis and plasma oxidation processes developed by our research group for the activation of the environmental friendly oxidants oxygen and hydrogen peroxide in the oxidative functionalisation of lignin and lignin model compounds. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com

2009-12-31T23:00:00Z Saladino, Raffaele Neri, Veronica Crestini, Claudia http://hdl.handle.net/2067/1820 2011-06-30T15:43:48Z 2009-12-31T23:00:00Z

Title: Role of clays in the prebiotic synthesis of sugar derivatives from formamide Authors: Saladino, Raffaele; Neri, Veronica; Crestini, Claudia Abstract: We describe here the role of montmorillonite KSF in the prebiotic synthesis of amino sugar derivatives starting from a mixture of formamide and formaldehyde as simple chemical precursors. Since amino sugars are key intermediates in the synthesis of complex nucleic acid derivatives, this procedure opens a novel pathway for the formation of nucleosides under plausible primordial conditions Description: L'articolo é disponibile sul sito dell'editore: http://www.informaworld.com

2009-12-31T23:00:00Z Saladino, Raffaele Neri, Veronica Crestini, Claudia Costanzo, Giovanna Graciotti, Michele Di Mauro, Ernesto http://hdl.handle.net/2067/1821 2011-06-30T15:45:55Z 2009-12-31T23:00:00Z

Title: The role of the formamide/zirconia system in the synthesis of nucleobases and biogenic carboxylic acid derivatives Authors: Saladino, Raffaele; Neri, Veronica; Crestini, Claudia; Costanzo, Giovanna; Graciotti, Michele; Di Mauro, Ernesto Abstract: We describe the one-pot synthesis of a large variety of nucleic acid bases and related compounds from formamide in the presence of zirconium minerals as catalysts. The major products observed are: purine, 2-hydroxy pyrimidine, 5-hydroxy pyrimidine, isocytosine, adenine, urea, and carbodiimide. The synthesis of low molecular weight amides and carboxylic acid derivatives (intermediates of extant metabolism) was also observed: glyoxylamide, glycolic-, lactic-, succinic-, oxalic-, fumaric-, and maleic acids. As the major problem in the origin of informational polymers is the instability of their precursors, we also investigated the effects of zirconia minerals on the stability of ribooligonucleotides in formamide and in water. The relevance of these findings with respect to the origin of informational polymers and primordial metabolism is discussed. Description: L'articolo é disponibile sul sito dell'editore: http://www.springerlink.com

2009-12-31T23:00:00Z Crestini, Claudia Perazzini, Raffaella Saladino, Raffaele http://hdl.handle.net/2067/1796 2011-06-30T14:36:27Z 2009-12-31T23:00:00Z

Title: Oxidative Functionalisation of Lignin by Layer-by-Layer Immobilised Laccases and Laccase Microcapsules Authors: Crestini, Claudia; Perazzini, Raffaella; Saladino, Raffaele Abstract: Laccase was either supported onto alumina particles or physically entrapped inside microcapsules. In both cases, the enzyme was protected by coating with oppositely charged polyelectrolytes by means of the layer-by-layer technique. The activities of these laccase particles and microcapsules were studied on softwood milled wood and kraft residual lignins, in the presence and absence of different mediators. Quantitative 31P NMR was used to determine the structural modifications induced in the lignin structures. Compared to the native enzyme, the laccase particles and microcapsules were found to be more reactive, showing higher conversions. Irrespective of the experimental conditions, the oxidation efficiency was enhanced by the presence of 1-hydroxybenzotriazole or violuric acid as the oxidation mediator. Differently immobilised laccases showed distinct reaction selectivities in the oxidative pattern of lignin. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com

2009-12-31T23:00:00Z