A theoretical study of alanine dipeptide and analogs
- Carnegie-Mellon Univ., Pittsburgh, PA (USA)
- Multiflow Computer, Inc., Branford, CT (USA)
We Present a preliminary report on the conformational and energetic analysis of the molecule (S)-2-acetylamino-N-methylpropanamide (alanine dipeptide) and an analog molecule, (S)-{alpha}-formylaminopropanamide, using high-quality ab initio methods. Alanine dipeptide and its analogs are of interest since they incorporate many of the structural features found in proteins, such as intramolecular hydrogen bonds, conformational flexibility, and a variety of chemical functionality. One purpose of this study is to provide a useful benchmark calculation, MP2/6-31+G{sup **}//HF/6-31+G{sup *}, for a number of conformations of the alanine system. Based on the comparison of these benchmark calculations with lower-level basis sets, HF/3-21G was chosen to generate a fully relaxed {phi}, {psi} dihedral map. These calculations are the first of their kind on systems of this size. Features of the {phi},{psi} alanine dipeptide map that are discussed include the energetically accessible conformations and possible pathways for their interconversion. In addition, we illustrate the importance of fully optimized geometries and the proper evaluation of correlation energies,
- OSTI ID:
- 6160010
- Report Number(s):
- CONF-8904365--
- Journal Information:
- International Journal of Quantum Chemistry; (USA), Journal Name: International Journal of Quantum Chemistry; (USA) Vol. 16; ISSN 0020-7608; ISSN IJQCB
- Country of Publication:
- United States
- Language:
- English
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