Artículos de revistas
H-1 NMR and theoretical studies on the conformational equilibrium of tryptophan methyl ester
Registro en:
Journal Of Molecular Structure. Elsevier Science Bv, v. 1050, n. 174, n. 179, 2013.
0022-2860
1872-8014
WOS:000326007200026
10.1016/j.molstruc.2013.07.024
Autor
Duarte, CJ
Cormanich, RA
Ducati, LC
Rittner, R
Institución
Resumen
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Selected (3)J(HH) coupling constants and theoretical calculations were used to explain the conformational equilibrium of L-tryptophan methyl ester (Trp-OMe) in several solvents. The obtained (3)J(H alpha H beta) values did not exhibit any significant variability and thus indicate that there are no conformational population variations for the side chain of the Trp-O-Me depending on the solvent. Moreover, the potential energy surfaces obtained at the B3LYP/cc-pVDZ theoretical level produced eight energy minima that were analysed by QTAIM and NBO methods. It was possible to conclude that the Trp-OMe conformational preferences were due to hyperconjugative effects involving the nonbonding electron pairs of the main chain nitrogen atom and certain antibonding orbitals (sigma(C4-C13)*, sigma(C1-C4)* and sigma(C4-H12)*) and also to the steric effects from the nonbonding electron pairs of oxygen atoms and the main and side chain of this system. (C) 2013 Elsevier B.V. All rights reserved. 1050 174 179 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) FAPESP [2012/03933-5, 2011/11098-6, 2011/01170-1, 2010/15764-4] CNPq [300379/2009-9]