Alessandro Venturini

Istituto per la Sintesi Organica e la Fotoreattività

A New Potent Inhibitor of Glycogen Phosphorylase Reveals the Basicity of the Catalytic Site

Posted by alevent on May 31, 2017

Accepted on Chemistry An European Journal

http://onlinelibrary.wiley.com/doi/10.1002/chem.201701591/full

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Cross-benzoin and Stetter-type reactions mediated by KOtBu-DMF via an electron-transfer process†

Posted by alevent on October 6, 2016

The condensation of aromatic α-diketones (benzils) with aromatic aldehydes (benzoin-type reaction) and chalcones (Stetter-type reaction) in DMF in the presence of catalytic (25 mol%) KOtBu is reported. Both types of umpolung processes proceed with good efficiency and complete chemoselectivity. On the basis of spectroscopic evidence (MS analysis) of plausible intermediates and literature reports, the occurrence of different ionic pathways have been evaluated to elucidate the mechanism of a model cross-benzoinlike reaction along with a radical route initiated by an electron-transfer process to benzil from the carbamoyl anion derived from DMF. This mechanistic investigation has culminated in a different proposal, supported by calculations and a trapping experiment, based on double electron-transfer to benzil with formation of the corresponding enediolate anion as the key reactive intermediate. A mechanistic comparison between the activation modes of benzils in KOtBu-DMF and KOtBu-DMSO systems is also described.

Daniele Ragno, Anna Zaghi, Graziano Di Carmine, Pier Paolo Giovannini, Olga Bortolini, Marco Fogagnolo, Alessandra Molinari, Alessandro Venturini* and Alessandro Massi*

Organic & Biomolecular Chemistry

DOI: 10.1039/c6ob01868h

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Anilino-Substituted Multicyanobuta-1,3-diene Electron Acceptors: TICT Molecules with Accessible Conical Intersections

Posted by alevent on October 28, 2015

TOCgraphABSTRACT: A theoretical investigation based on DFT, TD-DFT, and CASSCF/ CASPT2 methods has been carried out to elucidate the photophysics of two anilino- substituted pentacyano- and tetracyanobuta-1,3-dienes (PCBD and TCBD, respectively). These molecules exhibit exceptional electron-accepting properties, but their effective use in multicomponent systems for photoinduced electron transfer is limited because they undergo ultrafast (∼1 ps) radiationless deactivation. We show that the lowest-energy excited states of these molecules have a twisted intramolecular charge-transfer character and deactivate to the ground state through energetically accessible conical intersections (CIs). The topology of the lowest-energy CI, analyzed with a linear interpolation of the two branching-space vectors (g and h), indicates it is a sloped CI, ultimately responsible for the ultrafast deactivation of this class of compounds.

Filippo Monti, Alessandro Venturini,*, Artur Nenov, Francesca Tancini, Aaron D. Finke,
François Diederich,* and Nicola Armaroli*

J. Phys. Chem. A  2015, 119, 10677 – 10683

DOI: 10.1021/acs.jpca.5b09291

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Crossover of two power laws in the anomalous diffusion of a two lipid membrane

Posted by alevent on June 15, 2015

(Received 3 March 2015; accepted 19 May 2015; published online 2 June 2015)

Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2- oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal subdiffusional motion, which presents a crossover between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the crossover point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.

THE JOURNAL OF CHEMICAL PHYSICS 142, 215102 (2015)

Evangelos Bakalis,  Siegfried Höfinger,  Alessandro Venturini, and Francesco Zerbetto

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Modulating the thermostability of Endoglucanase I from Trichoderma reesei using computational approaches

Posted by alevent on March 25, 2015

cellulase, endoglucanase 1, molecular dynamics, protein engineering, Trichoderma reese

Abstract
In the last decades, effective cellulose degradation became a major point of interest due to the properties of cellulose as a renewable energy source and the widespread application of cellulases (the cellulose degrading enzymes) in many industrial processes. Effective bioconversion of lignocellulosic biomass into soluble sugars for ethanol production requires use of thermostable and highly active cellulases.
The library of current cellulases includes enzymes that can work at acidic and neutral pH in a wide temperature range. However, only few cellulases are reported to be thermostable. In order to alleviate this, we have performed a hybrid approach for the thermostabilization of a key cellulase, Endoglucanase I (EGI) from Trichoderma reesei. We combined in silico and in vitro experiments to modulate the thermostability of EGI. Four different predictive algorithms were used to set up a library of mutations. Three thermostabilizer mutations (Q126F, K272F, Q274V) were selected and molecular dynamics simulations at room temperature and high temperatures were performed to analyze the effect of the mutations on enzyme structure and stability. The mutations were then introduced into the endoglucanase 1 gene, using site-directed mutagenesis, and the effect of the mutations on enzyme structure and stability were determined. MD simulations supported the fact that Q126F, K272F and Q274V mutations have a thermostabilizing effect on the protein structure. Experimental studies validated that all of the mutants exhibited higher thermostability compared with native EGI albeit with a decrease in specific activity.

Gunseli Bayram Akcapinar, Alessandro Venturini, Pier Luigi Martelli, Rita Casadio and Ugur O. Sezerman

Protein Engineering, Design & Selection, 2015, 1–9
doi: 10.1093/protein/gzv012
Original Article

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Catalytic water splitting using an iridium-carbene complex: a theoretical study

Posted by alevent on March 13, 2014

Water Splitting

Alessandro Venturini*, Andrea Barbieri, Joost N. H. Reek, Dennis G. H. Hetterscheid*

Catalytic Water Splitting with an Iridium Carbene Complex: A Theoretical Study
[Full Paper]

mcontentPotential determines the path: DFT calculations on the mechanism of water oxidation mediated by iridium carbene complex [IrCp*(Me2NHC)(OH)]+ (Ir(OH)+) reveal several competing reaction pathways and that the applied potential favors certain reaction channels. IrV(=O)(O.)+ is found to be the calculated minimum-energy species and the rate-determining step (r.d.s.) is formation of the O-O bond, which occurs by intramolecular coupling of two oxo ligands (see figure; PCET: proton-coupled electron transfer).

Chem. Eur. J. 2014, 20, 5358 – 5368

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Optical Sensing in Diagnostics

Posted by alevent on March 13, 2014

Optical sensing devices are important tools for diagnostics in the biomedical
field. We briefly discuss the concepts of optical techniques as well as the
minimum requirements needed for optical sensing devices in order to afford
systems for low-cost and easy-to-use real-life applications.

2013_5_78_page14_image9

 

B. Ventura, I. Manet, A. Barbieri, A. Venturini,E. Bandini, N. Armaroli

CNR-ISOF Bologna

barbara.ventura@isof.cnr.it

La Chimica e L’ Industria Giu./Lug. 2013,81-83

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Workshops “Responsive Matrices for Solar Fuels” 28 October – 1 November 2013

Posted by alevent on November 3, 2013

Alessandro Venturini “Catalytic water splitting using an iridium-carbene complex: a theoretical study”

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An ESR and DFT revisitation of phosphonitroxides prompted by an ineffective ESR approach to the hydrophosphination of alkynes

Posted by alevent on July 27, 2013

Angelo Alberti,   Maurizio Guerra and  Alessandro Venturini

RSC Adv., 2013, published online
DOI: 10.1039/C3RA41929K
Received 19 Apr 2013, Accepted 17 Jul 2013, 2013,3, 17887-17897
An ESR investigation of the thermal hydrophosphination of 1-hexyne by five different secondary phosphines and phosphine-boranes did not lead to the observation of any radical, but in the presence of the spin trap MNP (2-methyl-2-nitrosopropane) several phosphonitroxides were detected. The unusually low phosphorus splitting exhibited by some of these species could be accounted for on the basis of DFT calculations. Although two phospho-substituted vinyl nitroxides were identified in the course of the hydrophosphination reaction, they could not be considered as evidence of the direct involvement of phosphorus-centred radicals.

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The HPC testbed of the Italian Grid Infrastructure(2013)

Posted by alevent on July 27, 2013

R. Alfieri, S. Arezzini, G. B. Barone, U. Becciani, M. Bencivenni, V. Boccia, D. Bottalico, L. Carracciuolo, D. Cesini, A. Ciampa, A. Costantini, S. Cozzini, R. De Pietri, M. Drudi, A. Ghiselli,E. Mazzoni, S. Ottani, A. Venturini, P. Veronesi,

 

 

Even though the Italian Grid Infrastructure (IGI) is a general purpose distributed platform, in the past it has been used mainly for serial computations. Parallel applications have been typically executed on supercomputer facilities or, in case of “not high-end” HPC applications, on local commodity parallel clusters. Nowadays, with the availability of multiple cores processors, Grid computing is becoming very attractive also for parallel applications but some problems exist in supporting of HPC applications on Grid environment. Here we describe the work made to set up a HPC testbed for “not high-end” HPC applications, based on IGI Grid technologies, to find solutions to those problems. Participating sites have been selected among the ones running HPC clusters in Grid environment. Each of them contributed with their specific HPC experience and their available resources to the present test, which encompasses an unprecedented large set of applications from different disciplines in the fields of astronomy, astrophysics, chemistry, climatology, material science and oceanography. In addition to computing resources sharing, the main contribution of each participant was the identification of the real requirements of his application also related to the current middleware limitations and then the realization of a test platform enhanced with additional HPC solutions and configurations developed in a tight collaboration between HPC administrators, users and IGI managers. The main work was on computational resources selection, data management and the definition, the deployment and the documentation of the software execution environment. The outcoming results of the testbed represent the basis of the HPC support in the IGI production infrastructure.

Published in:
Parallel, Distributed and Network-Based Processing (PDP), 2013 21st Euromicro International Conference on

Date of Conference: Feb. 27 2013-March 1 2013

Page(s): 241 – 248
ISSN : 1066-6192
E-ISBN : 978-0-7695-4939-2
Print ISBN: 978-1-4673-5321-2
INSPEC Accession Number: 13431804
Conference Location : Belfast
Digital Object Identifier : 10.1109/PDP.2013.42

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