6533b820fe1ef96bd127a4ae
RESEARCH PRODUCT
Stereoelectronic Requirements for Optimal Hydrogen-Bond-Catalyzed Enolization
Andrea HamzaPetri M. PihkoRik K. WierengaImre Pápaisubject
Models MolecularHydrogen bondOrganic ChemistryHydrogen BondingStereoisomerismOxyanionGeneral ChemistryCrystal structureKeto–enol tautomerismKetonesCarbon-Carbon Double Bond IsomerasesPhotochemistrySmall moleculeCatalysisMitochondriaCatalysischemistry.chemical_compoundCrystallographychemistryHumansThermodynamicsDensity functional theoryOxyanion holeAlgorithmsdescription
Protein crystallographic analysis of the active sites of enolizing enzymes and structural analysis of hydrogen-bonded carbonyl compounds in small molecule crystal structures, complemented by quantum chemical calculations on related model enolization reactions, suggest a new stereoelectronic model that accounts for the observed out-of-plane orientation of hydrogen-bond donors (HBDs) in the oxyanion holes of enolizing enzymes. The computational results reveal that the lone-pair directionality of HBDs characteristic for hydrogen-bonded carbonyls is reduced upon enolization, and the enolate displays almost no directional preference for hydrogen bonding. Positioning the HBDs perpendicular to the carbonyl plane induces strain in the catalyst-substrate complex, which is released upon enolization, resulting in more favorable kinetics and thermodynamics than the in-plane arrangement of HBDs.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2011-02-09 | Chemistry - A European Journal |