Chain conformation in polyretropeptides. II. Quantum mechanical and empirical force field calculations on 2,5,9,11-Tetraoxo-3,6,8,12-tetraza-tridecane, a model compound for the terpolymer of glycine and its retropeptides
✍ Scribed by Carlos Alemán; Jordi Puiggalí
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 885 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
A conformational study of the terpolymer of glycine and its retropeptides monomethylendiamine (gGly) and malonyl (mGly) with sequence: (-Gly-gGly-mGly-), is presented. First, we investigated the conformational preferences of the model molecule 2,5,9,11-tetraoxo-3,6,8,12-tetraza-tridecane using quantum mechanical calculations. The results indicated that the compound has a strong tendency to fold, giving intramolecular hydrogen bonds. Interestingly, the CI3 (intramolecular 13-membered ring hydrogen-bonded system) conformation, which is the pattern of an a-helix conformation, was characterized as a minimum. Force-field calculations in an infinite chain model showed that there are two preferred conformations to this regular polyretropeptide. These correspond to an a-helix and a 6-fold helix stabilized by intramolecular and intermolecular hydrogen bonds, respectively.