Dynamics of hydration water in proteins

Abstract

Abstract. Thermodynamic and transport properties of liquid water are determined essentially by inter-molecular hydrogen bonds and their dynamics. Because the molecular dynamics depends mostly on geometric constrains and dynamics of hydrogen bonds, it is shown that a simple statistics on the number of bonds, including at the vicinity of hydrophilic substrates describes well the temperature dependence of water diffusion on the surface of a small peptide.Experiments were performed by incoherent quasi-elastic neutron scattering giving information about the hydrogen bond lifetime and the residence time of the water molecules. In order to study the interactions between water molecules and a small hydrophobic peptide (an assembly of five monomers of alanine), the hydration level is changed step by step. The only motion of the first single water molecule of the structure is due to hydrogen libration. The first two added water molecules bind with the hydrophilic site of the peptide and have only the dynamics of the bond breaking. The other hydration molecules show fast diffusive motions on the surface of the peptide.

Comparison of Amino Acids Physico-Chemical Properties and Usage of Late Embryogenesis Abundant Proteins, Hydrophilins and WHy Domain

“…Interactions between amino acids side chains and waters contribute to the stabilization of the native, thus functional, protein conformation. The interactions between water molecules and a small hydrophobic pentapeptide ([Ala] 5 ), have been studied at controlled levels of hydration, by adding successively, up to 25 water molecules per peptide (this level corresponding to full hydration) [57] . The first added water molecules form naturally bonds with the hydrophilic part of the pentapeptide while the next added ones are confined to the surface of alanine without bond formation.…”

TargetedIn SituBiosynthetic Transcriptional Activation in Native Surface-Level Human Articular Chondrocytes during Lesion Stabilization

“… 61 - 63 Such proton charge shifts have been shown to produce mechanical alterations at articular cartilage surfaces 2 , 3 through electrochemomechanical coupling via site-specific hydrogen and disulfide bond alterations within constituent proteoglycan and collagen. 64 - 69 These targeted gradients at tissue surfaces modulate mechanical and electrochemical tissue matrix properties by altering fixed and variable charge densities while effecting consequent extracellular intrafibrillar hydration and osmotic character. 70 - 79 This physiochemical loading of accessible surface-based diseased tissue can alter the relative ratio of tension compression nonlinearity toward a state amenable to gentle shear deformation mechanical debridement of tissue already characterized by the deteriorating surface-layered shear properties of collagen fibril disruption and orientation changes, weak collagen-to-proteoglycan bonds, proteoglycan and lipid depletion, aberrant water content, and decreased fixed charge density.…”

Hydration water and peptide dynamics – two sides of a coin. A neutron scattering and adiabatic calorimetry study at low hydration and cryogenic temperatures

“…The steeper increase above 220-230 K is usually correlated with the so called dynamic transition, reflecting the increase in internal rotation and translation dynamics. 9,12,13,23,24,28,32 The hu 2 i values for a nominally dry sample (Fig. 1, inset) shows linear temperature dependence up to about 240 K, and a deviation from linearity above this temperature.…”

“…Nevertheless, many aspects regarding its particular structure near the surface and inside biological macromolecules as well as its link to biological function are still under discussion. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Proteins are known to have a ''limiting hydration'' necessary for function, and thus there must exist a link between hydration and protein functional properties.…”