An ab initio study of the peptide bond formation between alanine and glycine: electron correlation effects on the structure and binding energy

摘要: Abstract Ab initio methods are used to analyze the structure, energetics and binding energy of four possible dipeptides that can be formed from alanine glycine in gas phase. The structures peptides optimized using Hartree–Fock, second-order Moller–Plesset perturbation theory density functional (DFT). effect electron correlation is analyzed with special emphasis on calculated energies. Single-point calculations performed CCSD(T) MP2 geometries get some additional information effects. Electron effects zero-point vibrational corrections increase energy. At highest level, CCSD(T), we find energies for alanylalanine, alanylglycine, glycylalanine glycylglycine 4.86, 5.09, 5.61 5.89 kcal/mol, respectively. These numerical results suggest donates OH group easier than alanine. A comparison between DFT different basis sets made gives indication usefulness these bio-molecules peptide formation. Two functionals, B3LYP B3P86 differing by systematic inclusion diffuse polarization functions, method. obtained both functionals a includes functions reasonable agreement results. However, without including corrections, lead non-bonding molecule.