ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
α,β-Dehydro amino acid residues are known to constrain the peptide backbone to the β-bend conformation. A pentapeptide containing only one α,β dehydrophenylalanine (ΔPhe) residue has been synthesized and crystallized, and its solid state conformation has been determined. The pentapeptide Boc-Leu-Phe-Ala-ΔPhe-Leu-OMe (C39H55N5O8, Mw = 721.9) was crystallized from aqueous methanol. Monoclinic space group was P21, a = 10.290(2)°, b = 17.149(2)°, c = 12.179(2) Å, β = 96.64(1)° with two molecules in the unit cell. The x-ray (Mo Kα, λ = 0.7107A) intensity data were collected using a CAD4 diffractometer. The crystal structure was determined by direct methods and refined using least-squares technique. R = 4.4% and Rw = 5.4% for 4403 reflections having |F0| ≥ 3σ(|F0|). All the peptide links are trans and the pentapeptide molecule assumes 310-helical conformation. The mean φ,ψ values, averaged over the first four residues, are -64.4°, -22.4° respectively. There are three 4 → 1 intramolecular hydrogen bonds, characteristic of 310,-helix. In the crystal, the peptide helices interact through two head-to-tail. N—H—O intermolecular hydrogen bonds. The peptide molecules related by 21, screw symmetry form a skewed assembly of helices. © 1995 John Wiley & Sons, Inc.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360350202
