6533b858fe1ef96bd12b5a51
RESEARCH PRODUCT
Computational simulation of the lifetime of the methoxymethyl cation in water. A simple model for a glycosyl cation: when is an intermediate an intermediate?
J. Javier Ruiz PerníaIan H. WilliamsIñaki Tuñónsubject
Models MolecularChemistryTemperatureWaterMolecular Dynamics SimulationSurfaces Coatings and FilmsIonComputational simulationSolventMolecular dynamicschemistry.chemical_compoundModels ChemicalSimple (abstract algebra)Computational chemistryCationsMaterials ChemistryMoleculeQuantum TheoryGlycosylPhysical and Theoretical ChemistryQuantumdescription
A two-dimensional free-energy surface is constructed for transfer of the methoxymethyl cation between two water molecules. These atoms are treated quantum mechanically within a box of >1000 classical solvent water molecules, and the molecular dynamics of the whole system is considered at 300 K. This provides a simple model for glycosyl transfer in water. The best surface obtained (MPWB1K/6-31+G(d,p) corrected AMI/TIP3P) contains a shallow free-energy well corresponding to an oxacarbenium ion intermediate in a stepwise mechanism. Molecular dynamics analysis at three temperatures leads to a classical estimate of the lifetime of the methoxymethyl cation in water; when quantum corrections for vibrational zero-point energy are included, the lifetime is estimated to be 1 ps. This result is in complete agreement with the best experimental estimate and suggests that computational simulation is a reliable tool for elucidation of glycosyl-transfer mechanisms in enzymes and whether these involve glycosyl cations as intermediates.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2010-04-13 | The journal of physical chemistry. B |