Search results for "solvation"

Mechanism‐Dependent Modulation of Ultrafast Interfacial Water Dynamics in Intrinsically Disordered Protein Complexes

2018

Abstract The recognition of intrinsically disordered proteins (IDPs) is highly dependent on dynamics owing to the lack of structure. Here we studied the interplay between dynamics and molecular recognition in IDPs with a combination of time‐resolving tools on timescales ranging from femtoseconds to nanoseconds. We interrogated conformational dynamics and surface water dynamics and its attenuation upon partner binding using two IDPs, IBB and Nup153FG, both of central relevance to the nucleocytoplasmic transport machinery. These proteins bind the same nuclear transport receptor (Importinβ) with drastically different binding mechanisms, coupled folding–binding and fuzzy complex formation, resp…

Communication: Protein dynamical transition vs. liquid-liquid phase transition in protein hydration water

2013

In this work, we compare experimental data on myoglobin hydrated powders from elastic neutron scattering, broadband dielectric spectroscopy, and differential scanning calorimetry. Our aim is to obtain new insights on the connection between the protein dynamical transition, a fundamental phenomenon observed in proteins whose physical origin is highly debated, and the liquid-liquid phase transition (LLPT) possibly occurring in protein hydration water and related to the existence of a low temperature critical point in supercooled water. Our results provide a consistent thermodynamic/dynamic description which gives experimental support to the LLPT hypothesis and further reveals how fundamental …

Estimation of individual Gibbs energies of cation transfer employing the insertion electrochemistry of solid Prussian blue

2011

Abstract A novel method to determine the Gibbs energy of cation transfer between two miscible solvents is described. This method uses electrochemical data for the reversible cation-assisted solid-state reduction of Prussian blue using ferrocene as internal potential standard. Voltammetric data can be used for a direct measurement of the Gibbs energy of ion transfer from one solvent to another using midpeak potentials in solutions of suitable salts in each one of the solvents separately or mixtures of the solvents. Excess Gibbs energies of solvation in solvent mixtures can also be directly estimated. Gibbs energies of cation transfer of Li+, Na+ and K+ ions from water to MeOH, MeCN and DMSO …

The Role of Site-Specific Hydrogen Bonding Interactions in the Solvation Dynamics of N-Acetyltryptophanamide

2012

Measurements of the ultrafast broadband UV fluorescence of N-acetyltryptophanamide (NATA) provide detailed information on its relaxation patterns in three different solvents: methanol (MeOH), water and acetonitrile (ACN). Several processes leading to excited state solvation and cooling are found to occur on different characteristic time scales and are thoroughly analyzed. Comparison between protic MeOH and aprotic ACN allows one to single out a 12 Ps component in the former, which is attributed to the rearrangement of H-bonds existing between the protic solvent and excited NATA. This significantly stabilizes the excited state and provides the molecule with an efficient cooling mechanism. Th…

Ultrafast broadband fluorescnce up-conversion of N-acetyl-L-tryptophanamide (NATA)

2011

A Theoretical Study of the Favorskii Rearrangement. Calculation of Gas-Phase Reaction Paths and Solvation Effects on the Molecular Mechanism for the …

1997

The molecular mechanism of the α-chlorocyclobutanone transposition to yield cyclopropanecarboxylic acid, as a model of the Favorskii rearrangement, has been theoretically characterized in vacuo by means of ab initio molecular orbital procedures at the Hartree−Fock (HF) level of theory with the 6-31G* and 6-31+G* basis sets. The electron correlation has been estimated at the MP2/6-31G* level and calculations based on density functional theory, BLYP/6-31G*. The solvent effects are included at HF/6-31G* level by means of a polarizable continuum model. The questions related to the two accepted molecular mechanisms, the semibenzilic acid and the cyclopropanone transpositions, as well as the comp…

Cover Picture: Solvent-Adaptive Behavior of Oligospirobifluorenes at the Surface of Quartz Crystal Microbalances-A Conformational Process (ChemPlusCh…

2017

Untersuchung des Solvatationsgleichgewichts im ternären system Tetrachlormethan/Polymethylmethacrylat/Benzol durch kernmagnetische relaxation

1971

Im ternaren System CCl4/Polymethacrylate(PMMA)/Benzol tritt praferentielle Solvatation auf, Benzol ist in der Solvathulle des Polymeren angereichert. Es genugt eine Solvatationsgleichgewichtskonstante, um die praferentielle Solvatation bei variablen Konzentrationsverhaltnissen zu beschreiben. Gemessen wurde die Kernmagnetische Relaxationszeit T1 von Benzol in Abhangigkeit von der Polymerkonzentration. Der Vergleich mit analogen Messungen im System C6D6/PMMA/C6H6 ergibt fur die Solvatationsgleichgewichtskonstante K = (c32 · c10)/(c12 · c30) = 2,5 ± 0,5. Hierbei bedeuten: c10 die CCl4-Konzentrationen im „freien” Losungsmittel, c30 die Benzolkonzentrationen im „freien” Losungsmittel, c12 und c…

NMR relaxation and solvation equilibrium in the ternary system CCl4-polymethylmethacrylate-benzene

2007

In the ternary system CCl4-PMMA-benzene, benzene is preferentially adsorbed in the solvation shell of the polymer. One solvation equilibrium constant allows a satisfactory description of the preferential solvation for a large range of solvent compositions. The nuclear magnetic relaxation time T1 of benzene protons was measured for different values of the polymer concentration. The measurements are compared with analogous measurements in the system C6D6-PMMA-C6H6 where no preferential solvation is to be expected. For the system CCl4-PMMA-benzene the resulting dimensionless solvation equilibrium constant is K = c32c10/c12c30 = 2.5 ± 0.5 where c10 is the CCl4 concentration in the “free” solven…

Comparison and Rationalization of Droperidol Isostructural Solvate Stability: An Experimental and Computational Study

2014

In order to find a tool for comparison of solvate stability and to rationalize their relative stability, droperidol nonstoichiometric isostructural solvates were characterized experimentally and computationally. For the experimental evaluation of stability, three comparison tools were considered: thermal stability characterized by the desolvation rate, desolvation activation energy, and solvent sorption–desorption isotherms. It was found that the desolvation process was limited by diffusion, and the same activation energy values were obtained for all of the characterized solvates, while the solvent content in the sorption isotherm was determined by the steric factors. Therefore, the only cr…