| Autor: |
Guido Barone, Concetta Giancola, Carlo Andrea Mattia, Raffaella Puliti |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
Journal of Molecular Structure. 382:197-203 |
| ISSN: |
0022-2860 |
| DOI: |
10.1016/0022-2860(96)09310-6 |
| Popis: |
The crystal structure of N -acetylglycyl-L-prolinamide C 9 H 15 N 3 O 3 has been determined by single-crystal X-ray analysis to an R value of 0.046. The peptide linkage between Gly and Pro residues is in a distorted trans conformation. Main-chain conformation occurs for both residues in the F region of the conventional ϕ,ψ map for peptides. The prolific residue has a “type B” geometry. The ring conformation is not single atom puckered, and can be described as C 2 C β exo C γ endo , close to a pure twist form. The crystal packing is ruled by three intermolecular hydrogen bonds which involve all the donor groups. Wide layers of H-bonds grow parallel to the ab plane and separate along the c direction narrow apolar regions containing the proline residues at van der Waals distances. The temperatures and enthalpies of fusion and of a probable solid-solid transition, determined by differential scanning calorimetry, are discussed on the basis of the crystal features (density and hydrogenbond pattern) and in comparison with the corresponding parameters of the isomeric N -acetyl-L-prolylglycinamide. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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