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. 1986 Apr;83(7):1988–1992. doi: 10.1073/pnas.83.7.1988

Long polypeptide 310-helices at atomic resolution

Alfonso Bavoso *, Ettore Benedetti *, Benedetto Di Blasio *, Vincenzo Pavone *, Carlo Pedone *, Claudio Toniolo †, Gian Maria Bonora †
PMCID: PMC323215  PMID: 16593674

Abstract

The crystal-state preferred conformation of the terminally blocked homooctapeptide from the Cα,α-dimethylated α-aminoisobutyric acid (Aib) residue, pBrBz-(Aib)8-OBut, in which pBrBz is para-bromobenzoyl and OBut is tert-butoxy, determined by x-ray diffraction analysis using direct methods, was found to be a 310-helix stabilized by six consecutive intramolecular N—H....O=C hydrogen bonds of the C10-III (or III′) type. This is the first observation at atomic resolution of a regular 310-helix longer than two complete turns. The solid-state structural analysis was extended to the terminally blocked, α-aminoisobutyric acid-rich octapeptide corresponding to the 2-9 sequence of the peptaibol antibiotics emerimicins III and IV, pBrBz-Aib3-L-Val-Gly-L-Leu-Aib2-OMe. Again, this peptide adopts a (right-handed) 310-helical structure, although slightly distorted at the level of the L-leucine residue. The role of specific amino acid sequence and peptide main-chain length in stabilizing either the 310- or the α-helical conformation and their possible implications on the nature of the channel formed by peptaibol antibiotics in the membrane are also briefly discussed.

Keywords: crystal structure, conformation, peptaibol antibiotics, emerimicins

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1988

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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