title: Acid-base chemistry of frustrated water at protein interfaces.
abstract: Water molecules at a protein interface are often frustrated in hydrogen-bonding opportunities due to subnanoscale confinement. As shown, this condition makes them behave as a general base that may titrate side-chain ammonium and guanidinium cations. Frustration-based chemistry is captured by a quantum mechanical treatment of proton transference and shown to remove same-charge uncompensated anticontacts at the interface found in the crystallographic record and in other spectroscopic information on the aqueous interface. Such observations are untenable within classical arguments, as hydronium is a stronger acid than ammonium or guanidinium. Frustration enables a directed Grotthuss mechanism for proton transference stabilizing same-charge anticontacts.
authors.affiliation: Argentine Institute of Mathematics (I. A. M.), National Research Council (CONICET), Buenos Aires, Argentina.|Collegium Basilea, Institute for Advanced Study, Basel, Schweiz.
authors.forename: Ariel
authors.initials: A
authors.lastname: Fernández
mesh_terms: D000143:Acids / Q000737:chemistry*; D000468:Alkalies / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011506:Proteins / Q000737:chemistry*; D011789:Quantum Theory; D055672:Static Electricity; D014867:Water / Q000737:chemistry*
chemical_list: D000143:Acids; D000468:Alkalies; D011506:Proteins; D014867:Water
keywords: anticontacts; hydrogen-bond frustration; interfacial physics; molecular biophysics; protein-water interface; structural biology