Person: Bianco, Valentino
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First Name
Valentino
Last Name
Bianco
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Universidad Complutense de Madrid
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Item How the stability of a folded protein depends on interfacial water properties and residue-residue interactions(Journal of molecular liquids, 2017) Bianco, Valentino; Pagès-Gelabert, Neus; Coluzza, Ivan; Franzese, GiancarloProteins tend to adopt a single or a reduced ensemble of configurations at natural conditions [1], but changes in temperature T and pressure P induce their unfolding. Therefore for each protein there is a stability region (SR) in the T–P thermodynamic plane outside which the biomolecule is denaturated. It is known that the extension and shape of the SR depend on i) the specific protein residue-residue interactions in the native state of the amino acids sequence and ii) the water properties at the hydration interface. Here we analyze by Monte Carlo simulations the different coarse-grained protein models in explicit water how changes in i) and ii) affect the SR. We show that the solvent properties ii) are essential to rationalize the SR shape at low T and high P and that our findings are robust with respect to parameter changes and with respect to different protein models, representative of the ordered and disordered proteins. These results can help in developing new strategies for the design of novel synthetic biopolymers.Item Proteins Are Solitary! Pathways of Protein Folding and Aggregation in Protein Mixtures(The Journal of Physical Chemistry Letters, 2019) Bianco, Valentino; Alonso-Navarro, Miren; Di Silvio, Desire; Moya, Sergio; Cortajarena L., Aitziber; Coluzza, IvanWe present a computational and experimental study on the folding and aggregation in solutions of multiple protein mixtures at different concentrations. We show how in protein mixtures, each component is capable of maintaining its folded state at desensitises higher then the one at which they would precipitate in single species solutions. We demonstrate the generality of our observation over many different proteins using computer simulations capable of fully characterising the cross-aggregation phase diagram of all the mixtures. Dynamic light Scattering experiments were performed to evaluate the aggregation of two proteins, the bovine serum albumin (BSA) and the consensus tetratricopeptide repeat (CTPR), in solutions of one or both proteins. The experiment confirm our hypothesis and the simulations. These findings elucidate critical aspects on the cross-regulation of expression and aggregation of proteins exerted by the cell and on the evolutionary selection of folding and not-aggregating protein sequences, paving the way for new experimental tests.Item Hydrogen bond correlated percolation in a supercooled water monolayer as a hallmark of the critical region(Journal of Molecular Liquids, 2019) Bianco, Valentino; Franzese, GiancarloNumerical simulations for a number of water models have supported the possibility of a metastable liquid-liquid critical point (LLCP) in the deep supercooled region. Here we consider a theoretical model for a supercooled liquid water monolayer and its mathematical mapping onto a percolation problem. The mapping allows us to identify the finite-size clusters at any state-point, and the infinite cluster at the critical point, with the regions of correlated hydrogen bonds (HBs). We show that the percolation line coincides with the first-order liquid-liquid phase transition ending at the LLCP. At pressures below the LLCP, the percolation line corresponds to the strong maxima of the thermodynamic response functions and to the locus of maximum correlation length (Widom line). At higher pressures, we find a percolation transition with a positive slope and we discuss its possible relation with the thermodynamics.Item Re-entrant limits of stability of the liquid phase and the Speedy scenario in colloidal model systems(Journal of chemical physics, 2017) Rovigatti, Lorenzo; Bianco, Valentino; Tavares, José María; Sciortino, FrancescoA re-entrant gas-liquid spinodal was proposed as a possible explanation of the apparent divergence of the compressibility and specific heat off supercooling water. Such a counter-intuitive possibility, e.g., a liquid that becomes unstable to gas-like fluctuations on cooling at positive pressure, has never been observed, neither in real substances nor in off-lattice simulations. More recently, such a reentrant scenario has been dismissed on the premise that the re-entrant spinodal would collide with the gas-liquid coexisting curve (binodal) in the pressure-temperature plane. Here we study, numerically and analytically, two previously introduced one-component patchy particle models that both show (i) a re-entrant limit of stability of the liquid phase and (ii) a re-entrant binodal, providing a neat in silico (and in charta) realization of such unconventional thermodynamic scenario.Item Globulelike Conformation and Enhanced Diffusion of Active Polymers(Physical Review Letters, 2018) Bianco, Valentino; Locatelli, Emanuele; Malgaretti, PaoloWe study the dynamics and conformation of polymers composed by active monomers. By means of Brownian dynamics simulations we show that, when the direction of the self-propulsion of each monomer is aligned with the backbone, the polymer undergoes a coil-to-globulelike transition, highlighted by a marked change of the scaling exponent of the gyration radius. Concurrently, the diffusion coefficient of the center of mass of the polymer becomes essentially independent of the polymer size for sufficiently long polymers or large magnitudes of the self-propulsion. These effects are reduced when the self-propulsion of the monomers is not bound to be tangent to the backbone of the polymer. Our results, rationalized by a minimal stochastic model, open new routes for activity-controlled polymers and, possibly, for a new generation of polymer-based drug carriers.Item In silico evidence that protein unfolding is as a precursor of the protein aggregation(ChemPhysChem, 2019) Bianco, Valentino; Franzese, Giancarlo; Coluzza, IvanWe present a computational study on the folding and aggregation of proteins in an aqueous environment, as a function of its concentration. We show how the increase of the concentration of individual protein species can induce a partial unfolding of the native conformation without the occurrence of aggregates. A further increment of the protein concentration results in the complete loss of the folded structures and induces the formation of protein aggregates. We discuss the effect of the protein interface on the water fluctuations in the protein hydration shell and their relevance in the protein-protein interaction.Item Anomalous Behavior in the Nucleation of Ice at Negative Pressures(Physical Review Letters, 2021) Bianco, Valentino; Montero De Hijes, Pablo; Cintia P. Lamas; Sanz García, Eduardo Santiago; Carlos Vega; Vega De Las Heras, CarlosIce nucleation is a phenomenon that, despite the relevant implications for life, atmospheric sciences, and technological applications, is far from being completely understood, especially under extreme thermodynamic conditions. In this work we present a computational investigation of the homogeneous ice nucleation at negative pressures. By means of the seeding technique we estimate the size of the ice critical nucleus Nc for the TIP4P/Ice water model. This is done along the isotherms 230, 240, and 250 K, from positive to negative pressures until reaching the liquid-gas kinetic stability limit (where cavitation cannot be avoided). We find that Nc is nonmonotonic upon depressurization, reaching a minimum at negative pressures in the doubly metastable region of water. According to classical nucleation theory we establish the nucleation rate J and the surface tension γ, revealing a retracing behavior of both when the liquid-gas kinetic stability limit is approached. We also predict a reentrant behavior of the homogeneous nucleation line. The reentrance of these properties is related to the reentrance of the coexistence line at negative pressure, revealing new anomalies of water. The results of this work suggest the possibility of having metastable samples of liquid water for long times at negative pressure provided that heterogeneous nucleation is suppressed.