Three complete turns of a 310-helix at atomic resolution: the crystal structure of Z-(Aib)11-OtBu

✍ Scribed by Dr Renate Gessmann; Hans Brückner; Kyriacos Petratos

• Book ID: 105360305
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 344 KB
• Volume: 9
• Category: Article
• ISSN: 1075-2617
• DOI: 10.1002/psc.490

✦ Synopsis

Abstract

The crystal structure of the synthetic protected oligopeptide Z‐(Aib)~11~‐O__t__Bu was determined by x‐ray crystallography. The undecapeptide folds in a regular 3~10~‐helix with nine consecutive 4 → 1 hydrogen bonds. At present, this is the largest available structure of a homopeptide (including homopeptides consisting of standard amino acids) and also the longest observed regular 3~10~‐helix at atomic resolution. Z‐(Aib)~11~‐O__t__Bu crystallizes readily from hot ethanol–water mixture and is one of the crystals in which no solvent molecule is co‐crystallized. In the crystal head‐to‐tail hydrogen bonded columns are formed in the [1 0 1] direction. Each helical column is surrounded by six others, whereby two are packed in parallel and four in antiparallel fashion. Helical columns are packed via apolar crystal contacts. The crystal structure of Z‐(Aib)~11~‐O__t__Bu is compared with the crystal structures of Z‐(Aib)~10~‐O__t__Bu and Z‐(Aib)~9~‐O__t__Bu. The similarities and differences are analysed. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.