Water at the protein surface is coupled to protein structure and function. Water reorientation represents the major contribution to the overall ultra-fast hydration response of proteins. We probe the rotational dynamics of biological water with large scale ab initio molecular dynamics simulations running entirely on graphical processing units (GPU). The entire cone snail toxin protein was treated quantum mechanically, providing an accurate and flexible description of protein polarization and charge transfer effects without any ad hoc parameters. We compare the ab initio results to those of classical simulations, wherein the protein was described by fixed-charge models. This allows us to identify a group of water molecules with distinct dynamical properties that are not reproduced in the classical simulations, presumably, due to neglecting the 'electronic flexibility' effects in the protein. We discuss the apparent correlation between these water molecules and toxin binding which is an indispensable part of its biological function.

Rotational dynamics of water near protein binding sites: Insights from ab initio molecular dynamics simulation

246th National Meeting (2013)

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