@article {2007|1828, title = {How protein surfaces induce anomalous dynamics of hydration water}, journal = {J. Phys. Chem. B}, volume = {111}, number = {26}, year = {2007}, pages = {7584{\textendash}90}, abstract = {Water around biomolecules slows down with respect to pure water, and both rotation and translation exhibit anomalous time dependence in the hydration shell. The origin of such behavior remains elusive. We use molecular dynamics simulations of water dynamics around several designed protein models to establish the connection between the appearance of the anomalous dynamics and water-protein interactions. For the first time we quantify the separate effect of protein topological and energetic disorder on the hydration water dynamics. When a static protein structure is simulated, we show that both types of disorder contribute to slow down water diffusion, and that allowing for protein motion, increasing the spatial dimensionality of the interface, reduces the anomalous character of hydration water. The rotation of water is, instead, altered by the energetic disorder only; indeed, when electrostatic interactions between the protein and water are switched off, water reorients even faster than in the bulk. The dynamics of water is also related to the collective structure{\textendash}{\`a} voir the hydrogen bond (H-bond) network{\textendash}formed by the solvent enclosing the protein surface. We show that, as expected for a full hydrated protein, when the protein surface offers pinning sites (charged or polar sites), the superficial water-water H-bond network percolates throughout the whole surface, hindering the water diffusion, whereas it does not when the protein surface lacks electrostatic interactions with water and the water diffusion is enhanced.}, author = {Pizzitutti, Francesco and Marchi, Massimo and Sterpone, Fabio and Rossky, Peter J} } @article {2006|1441, title = {Molecular modeling and simulation of water near model micelles: diffusion, rotational relaxation and structure at the hydration interface}, journal = {J. Phys. Chem. B}, volume = {110}, number = {23}, year = {2006}, pages = {11504{\textendash}10}, author = {Sterpone, Fabio and Marchetti, Gino and Pierleoni, Carlo and Marchi, Massimo} } @article {2006|1827, title = {Structure and dynamics of hydrogen bonds in the interface of a C12E6 spherical micelle in water solution: a MD study at various temperatures}, journal = {J. Phys. Chem. B}, volume = {110}, number = {37}, year = {2006}, pages = {18254{\textendash}61}, author = {Sterpone, Fabio and Pierleoni, Carlo and Briganti, Giuseppe and Marchi, Massimo} } @article {2004|1826, title = {Molecular Modeling and Simulations of AOT{\^a}{\textasciicircum}{\textquoteright}Water Reverse Micelles in Isooctane:{\^a}{\texteuro}{\textperthousand} Structural and Dynamic Properties}, journal = {J. Phys. Chem. B}, volume = {108}, number = {50}, year = {2004}, pages = {19458{\textendash}19466}, author = {Abel, St{\'e}phane and Sterpone, Fabio and Bandyopadhyay, Sanjoy and Marchi, Massimo} } @article {2002|1817, title = {Water rotational relaxation and diffusion in hydrated lysozyme}, journal = {J. Am. Chem. Soc.}, volume = {124}, number = {23}, year = {2002}, month = {jun}, pages = {6787{\textendash}91}, abstract = {This paper is concerned with the dynamics of water around a small globular protein. Dipolar second-rank relaxation time and diffusion properties of surface water were computed by extensive molecular dynamics simulations of lysozyme in water which lasted a total of 28 ns. Our results indicate that the rotational relaxation of water in the vicinity of lysozyme is 3-7 times slower than that in the bulk depending on how the hydration shell is defined in the calculation. We have also verified that the dynamics of water translational diffusion in the vicinity of lysozyme have retardations similar to rotational relaxation. This is a common assumption in nuclear magnetic relaxation dispersion (NMRD) studies to derive residence times. In contrast to bulk water dynamics, surface water is in a dispersive diffusion regime or subdiffusion. Very good agreement of dipolar second-rank relaxation time with NMRD estimates is obtained by using appropriate dimensions of the hydration shell. Although our computed second-rank dipolar retardations are independent of the water model, SPC/E describes more realistically the time scale of the water dynamics around lysozyme than does TIP3P.}, author = {Marchi, Massimo and Sterpone, Fabio and Ceccarelli, Matteo} }