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

M. A. Zamora, H. A. Baldoni, A. M. Rodriguez, R. D. Enriz, C. P. Sosa, A. Perczel, A. Kucsman, O. Farkas, E. Deretey, J. C. Vank, I. G. Csizmadia

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14 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)832-844
Number of pages13
JournalCanadian Journal of Chemistry
Volume80
Issue number7
DOIs
Publication statusPublished - Sep 18 2002

Keywords

  • AIM analysis
  • Ab initio and DFT geometry optimization
  • Intramolecular hydrogen bonding
  • L-cysteine diamides
  • Side-chain potential-energy surface

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Organic Chemistry

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