More than one dynamic crossover in protein hydration water

Details More than one dynamic crossover in protein hydration water More than one dynamic crossover in protein hydration water

2009-07-10

arxiv.org/abs/0907.1810v2

Physics

Condensed Matter

Soft Condensed Matter

Scientific paper

Studies of liquid water in its supercooled region have led to many insights into the structure and behavior of water. While bulk water freezes at its homogeneous nucleation temperature of approximately 235 K, for protein hydration water, the binding of water molecules to the protein avoids crystallization. Here we study the dynamics of the hydrogen bond (HB) network of a percolating layer of water molecules, comparing measurements of a hydrated globular protein with the results of a coarse-grained model that has been shown to successfully reproduce the properties of hydration water. With dielectric spectroscopy we measure the temperature dependence of the relaxation time of protons charge fluctuations. These fluctuations are associated to the dynamics of the HB network of water molecules adsorbed on the protein surface. With Monte Carlo (MC) simulations and mean--field (MF) calculations we study the dynamics and thermodynamics of the model. In both experimental and model analyses we find two dynamic crossovers: (i) one at about 252 K, and (ii) one at about 181 K. The agreement of the experiments with the model allows us to relate the two crossovers to the presence of two specific heat maxima at ambient pressure. The first is due to fluctuations in the HB formation, and the second, at lower temperature, is due to the cooperative reordering of the HB network.

Affiliated with

Also associated with

No associations

Rating

More than one dynamic crossover in protein hydration water does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with More than one dynamic crossover in protein hydration water, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and More than one dynamic crossover in protein hydration water will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-164723