Concentration dependence of hydration water in a model peptide

Abstract

The molecular dynamics of aqueous solutions of a model amphiphilic peptide is studied as a function of concentration by broad-band light scattering experiments. Similarly to protein aqueous solutions, a considerable retardation, of about a factor 6-8, of hydration water dynamics with respect to bulk water is found, showing a slight dependence on solute concentration. Conversely, the average number of water molecules perturbed by the presence of peptide, i.e. the hydration number, appears to be strongly modified by adding solute. Its behaviour, decreasing upon increasing concentration, can be interpreted considering the random close-to-contact condition experienced by solute particles. Overall, the present findings support the view of a "long range" effect of peptides on the surrounding water, extending beyond the first two hydration shells.

Interfacial water at the trialanine hydrophilic surface: a DFT electronic structure and bottom-up investigation

“…[5][6][7][8][9][10][11][12]21 The formation of strong H-bonds, which disrupts the water structure and avoids synergistic water molecule reorientation in the immediate vicinity of the peptide, is responsible for the slowdown of water motion. [5][6][7][8][9][10][11][12]21 The formation of strong H-bonds, which disrupts the water structure and avoids synergistic water molecule reorientation in the immediate vicinity of the peptide, is responsible for the slowdown of water motion.…”

“…All these features are in accordance with many pieces of experimental evidence and many molecular dynamic studies, which suggested a small number of water molecules coordinated to acceptor and donor groups of peptides. [5][6][7][8][9][10][11][12]21 The formation of strong H-bonds, which disrupts the water structure and avoids synergistic water molecule reorientation in the immediate vicinity of the peptide, is responsible for the slowdown of water motion.…”

“…[1][2][3][4] Very simple di-and tripeptides dissolved in an aqueous environment have attracted great attention because, due to their chemical simplicity, it is presumably easy to understand molecular properties and water-peptide interactions. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Although there is no exhaustive experimental technique that directly probes water/peptide geometrical arrangement, neutron scattering, 5 NMR, 6,7 TeraHz, [8][9][10] dielectric relaxation, 11 and fluorescent 12 spectroscopies have provided invaluable information about dynamic processes occurring at the water/peptide interface. All these techniques have the time resolution in the picosecond range, hence appropriate for investigating the network of hydrogen-bonds.…”

Quantum Mechanics Approach to Hydration Energies and Structures of Alanine and Dialanine

“…[9][10][11][12] From the experimental point of view,t here is no exhaustive experimental technique that directly probess pecific biomolecule-water interactions in solution, sincec hanges in geometricala rrangement are too fast, on the picosecondt imescale. [13] Nevertheless, neutron scattering, [14] NMR, [15,16] terahertz, [17][18][19] dielectric relaxation, [20] and fluorescence [21] spectroscopy has shownt hat molecular reorientation occurs more slowly than in bulk water,m ainly because of the peptide-water H-bonds and the topologically het-erogeneous nature of ap eptide surface, which disrupts the synergistic water-water reorientation mechanisms.…”

Dynamical changes in hydration water accompanying lysozyme thermal denaturation

“…The bio-functionality of a protein is directly linked to the amino acid sequence and structure that characterizes the native protein state; furthermore, it is strongly dependent on the solvent, i.e., water, which actually functions as an amino acid [4]. Dry proteins exhibit no biological activity and require at least a water monolayer (a first hydration shell) covering their surface to function as proteins [5][6][7]. Water in the form of internal water is also an essential part of the three-dimensional structure of a protein [8,9].…”