The Journal of Physical Chemistry A · 2003 · 25 citations · 41 references
Natural SciencesChemistryComputational ChemistryComputational Medicinal ChemistryQuantum ChemistryAb Initio MethodsAmino Acid ChemistryAmino Acid StructureConformational AnalysisMolecular Orbital TheoryMolecular StructureAb Initio CalculationsAromatic Side Chain InteractionsConformational StabilityIndependent VariablesMolecular Conformation AnalysisMolecular Electrostatic PotentialMolecular Modeling Of Amino Acid ConformationsRamachandran Analysis
The full conformational space of N -acetyl- l -glutamine- N -methylamide was explored by ab initio (RHF/3-21G and RHF/6-31G(d)) and DFT (B3LYP/6-31G(d)) computations. On the Ramachandran hypersurface of four independent variables, E = E (φ,ψ,χ 1,χ 2 ), 59 conformers were located instead of the expected 3 4 = 81 stable structures. The relative stabilities of the various conformers were analyzed in terms of side chain/backbone interactions covering different hydrogen bonding types by using the theory of atoms in molecules (AIM) and molecular electrostatic potentials (MEPs). The theoretical results were compared with some experimental data (NMR and X-ray).
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