Dynamics of Protein Hydration Water

TL;DR

This study investigates the dielectric properties of lysozyme solutions across a wide temperature range, revealing bimodal hydration water dynamics and insights into the fragile-to-strong water transition.

Contribution

It provides new experimental data on hydration water dynamics at subzero temperatures, including the No Man's Land, highlighting bimodality and its relation to water's transition behaviors.

Findings

Hydration water exhibits bimodal dynamics.

Unfreezable hydration water persists below freezing.

Results support the fragile-to-strong water transition hypothesis.

Abstract

We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range including the so-called No Man's Land (160 - 235 K). The obtained results prove the bimodality of the hydration shell dynamics and are discussed in the context of the highly-debated fragile-to-strong transition of water.