Ab initio conformational analysis of N- and C-terminally-protected valyl-alanine dipeptide model

Cindy P. Chun, Ashton A. Connor, Gregory A. Chass

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Ab initio conformational analysis of the dipeptide Ac-Valine-Alanine-NHMe was performed and optimized at the RHF/3-21g level of theory in an attempt to characterize the folding of short peptides. A topological scan of alanine's (Ala) ψ and φ rotors was carried out with valine (Val) in the βL geometry to construct a Ramachandran surface in two- and three-dimensions. It was observed that Val sterically dominates the conformations of Ala. Of the 243 possible conformers in this study, 202 were found. Those that were not found had converged to a different geometry of lower energy and greater stability. The γL and εL conformers of Ala were favoured, and 47 of the found conformers can be classified as potential β-turns according to the traditional backbone torsional definitions. However, the potentially most stable conformer, αDaγL, was not in one of these regions of the Ramachandran surface. Thus, β-turns may not be inherent conformations of the Val-Ala dipeptide, but may arise preferentially within protein structures due to certain steric effects from the surrounding environment.

Original languageEnglish (US)
Pages (from-to)177-184
Number of pages8
JournalJournal of Molecular Structure: THEOCHEM
Issue number3
StatePublished - Sep 30 2005


  • β-Turn
  • Ab initio
  • Ac-Valine-Alanine-NHMe
  • Dipeptide model
  • RHF/3-21G

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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