6533b85efe1ef96bd12bf482

RESEARCH PRODUCT

Intramolecular proton transfer of serine in aqueous solution. Mechanism and energetics

Estanislao SillaDaniel RinaldiFrancisco R. TortondaManuel F. Ruiz-lópezIñaki Tuñón

subject

SolventSerineQuantitative Biology::BiomoleculesAqueous solutionChemistryComputational chemistryIntramolecular forceIonizationNon-equilibrium thermodynamicsHydrogen atomDielectricPhysical and Theoretical Chemistry

description

Serine amino acid in aqueous solution is theoretically studied at the B3PW91/6-31+G** level using a dielectric continuum solvent model. Neutral and zwitterionic structures in the gas phase and in solution are described and the proton-transfer mechanism is discussed. A neutral conformation in which the carboxyl hydrogen atom is already oriented toward the amino group seems to be the absolute energy minimum in the gas phase and the most stable neutral form in solution. The absolute energy minimum in solution is a zwitterionic form. The energy barrier for proton transfer is predicted to be very small, in particular when zero-point-energy contributions are added. Our calculations allow the dynamic aspects of the ionization mechanism to be discussed by incorporating nonequilibrium effects.

https://doi.org/10.1007/s002149900109