ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The crystal and molecular structure of N-benzyloxycarbonyl-α-aminoisobutyryl-L-prolyl methylamide, the amino terminal dipeptide fragment of alamethicin, has been determined using direct methods. The compound crystallizes in the orthorhombic system with the space group P212121. Cell dimensions are a = 7.705 Å, b = 11.365 Å, and c = 21.904 Å. The structure has been refined using conventional procedures to a final R factor of 0.054. The molecular structure possesses a 4 → 1 intramolecular N-H - O hydrogen bond formed between the CO group of the urethane moiety and the NH group of the methylamide function. The peptide backbone adopts the type III β-turn conformation, with φ2 = -51.0°, ψ2 = -39.7°, φ3 = -65.0°, ψ3 = -25.4°. An unusual feature is the occurrence of the proline residue at position 3 of the β-turn. The observed structure supports the view that Aib residues initiate the formation of type III β-turn conformations. The pyrrolidine ring is puckered in Cγ-exo fashion.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1979.360180704
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