Stickiness of the Hydrogen Bond

Abstract

The dielectric response of bulk water follows laws of continuum electrostatics, a scheme often extrapolated without justification to treat confined interfacial water, where the Debye polarization ansatz breaks down and discrete effects matter. Reconciling the discrete behavior with the continuum equations requires a conceptual leap, all the more so when assessing the electrostatic impact of exclusion of individual water molecules. This work takes up the challenge and identifies the nanoscale stickiness of a preformed water-embedded hydrogen bond as phenomena not encompassed by continuum laws but quantitatively predictable when adopting a nanoscale theory of dielectric response holding down to molecular dimensions. Nanoscale stickiness is known to drive basic cellular events and has been measured using a molecular force probe but its physical underpinnings and computation have been lacking so far. The findings reported may impact molecular design in bio-nanotechnology and shed light on standing challenges in biophysics, especially on the protein folding problem, where organized compaction of the protein chain following nucleating intramolecular hydrogen bonding demands explanation.