info:eu-repo/semantics/article
Peptide model XXVIII: An exploratory ab initio and density functional study on the side-chain-backbone interaction in N-acetyl-L-cysteine-N-methylamide and N-formyl-L-cysteinamide in their γL-backbone conformations
Fecha
2002-07-01Registro en:
Zamora, Miguel Angel; Baldoni, Hector Armando; Rodriguez, Ana Maria; Enriz, Ricardo Daniel; Sosa, Carlos P.; et al.; Peptide model XXVIII: An exploratory ab initio and density functional study on the side-chain-backbone interaction in N-acetyl-L-cysteine-N-methylamide and N-formyl-L-cysteinamide in their γL-backbone conformations; National Research Council Canada-NRC Research Press; Canadian Journal of Chemistry; 80; 7; 1-7-2002; 832-844
0008-4042
1480-3291
CONICET Digital
CONICET
Autor
Zamora, Miguel Angel
Baldoni, Hector Armando
Rodriguez, Ana Maria
Enriz, Ricardo Daniel
Sosa, Carlos P.
Perczel, András
Kucsman, Árpád
Farkas, Ödön
Deretey, Eugen
Vank, Judith C.
Csizmadia, Imre Gyula
Resumen
A conformational and electronic study on the energetically preferred conformations (γL) of N- and C-protected L-cysteine (P-CONH-CH(CH2SH)-CONH-Q, where P and Q may be H or Me) was carried out. After restraining the backbone (BB) conformation to its global minimum (γL or C7eq), all nine possible side-chain (SC) conformations were subjected to geometry optimization at the HF/3-21G and the B3LYP/6-31G(d,p) levels of theory. Seven of the nine side-chain conformers were located on the potential-energy surface. All conformers were subjected to an AIM (atoms in molecules) analysis. This study indicates that three of the seven optimized conformers exhibited either or both SC → BB- or BB → SC-type intramolecular hydrogen bonding. Five conformers, however, had distances between a proton and a heteroatom that suggested hydrogen bonding.