ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The protected dipeptide Boc-Aib-Pro-OBzl, C21H30N2O5, crystallizes in the orthorhombic space group P212121, with a = 12.820, b = 10.529, c = 16.548Å, and Z = 4. The crystal structure has been solved by direct methods and refined to an R value of 0.074 for 1352 reflections. The Boc-Aib-Pro-OBzl molecule has been shown to adopt an unfolded conformation in the solid state with φAib = 50.5°, ΨAib = 45.3°, φPro = -64.6°, and ΨPro = 148.1°. The result is in marked contrast with the reported crystal structure of Cbz-Aib-Pro-NHMe, which adopts an intramolecularly hydrogen-bonded β-turn conformation. Comparison with 13 reported conformations of Aib-Pro sequences in the crystalline state revealed that the Aib-Pro sequence adopts an unfolded conformation if the residue that immediately follows the dipeptide sequence possesses no hydrogen available for hydrogen bonding, while a β-turn conformation is preferred if the Pro residue is followed by an NH group. Correlation between pyrrolidine ring puckering of the Pro residue and main-chain conformation in Aib-Pro sequences is discussed.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360260110
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