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Solid-state conformations of α-Aminoisobutyryl-L-prolyl sequences: Crystal structure of Boc-Aib-L-Pro-OBzl

✍ Scribed by Masao Kawai; Yasuo Butsugan; Keiichi Fukuyama; Tooru Taga

Publisher
Wiley (John Wiley & Sons)
Year
1987
Tongue
English
Weight
613 KB
Volume
26
Category
Article
ISSN
0006-3525

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✦ Synopsis

The protected dipeptide Boc-Aib-Pro-OBzl, CzlH,NzO,,s crystallizes in the orthorhombic space group P2,2121, with a = 12.820, b = 10.529, c = 16.548 A, and Z = 4. The crystal structure has been solved by direct methods and relined 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 statcwith +hb = 50.5O, J'hb = 45.3O, +Ro = -6I4.6O, and = 148.1'. Th. result is in marked contrast with the reported crystal structure of Cbz-Aib-Pro-NHMe, which adopts an intramolecularly hydrogen-bcnded 8-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 F-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.

📜 SIMILAR VOLUMES

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The crystal and molecular structure of N-benzyloxycarbonyl-a-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 P212~21. Cell dimensions are a

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