Influence of ionization on the conformational preferences of peptide models. Ramachandran surfaces ofN-formyl-glycine amide andN-formyl-alanine amide radical cations
| Autor: | Juan Bertrán, Adrià Gil, Mariona Sodupe |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular Alanine Protein Conformation Chemistry Glycine General Chemistry Interaction energy Polarizable continuum model Computational Mathematics chemistry.chemical_compound Protein structure Radical ion Computational chemistry Cations Ionization Amide Solvents Quantum Theory Computer Simulation Solvent effects Ramachandran plot |
| Zdroj: | Journal of Computational Chemistry. 30:1771-1784 |
| ISSN: | 1096-987X 0192-8651 |
| Popis: | Ramachandran maps of neutral and ionized HCO-Gly-NH2 and HCO-Ala-NH2 peptide models have been built at the B3LYP/6-31++G(d,p) level of calculation. Direct optimizations using B3LYP and the recently developed MPWB1K functional have also been carried out, as well as single-point calculations at the CCSD(T) level of theory with the 6-311++G(2df,2p) basis set. Results indicate that for both peptide models ionization can cause drastic changes in the shape of the PES in such a way that highly disallowed regions in neutral PES become low-energy regions in the radical cation surface. The structures localized in such regions, epsilonL+* and epsilonD+* are highly stabilized due to the formation of 2-centre-3-electron interactions between the two carbonyl oxygens. Inclusion of solvent effects by the conductor-like polarizable continuum model (CPCM) shows that the solute-solvent interaction energy plays an important role in determining the stability order. |
| Databáze: | OpenAIRE |
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