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Aib Residues in Peptaibiotics and Synthetic Sequences: Analysis of Nonhelical Conformations

Aravinda, Subrayashastry and Shamala, Narayanaswamy and Balaram, Padmanabhan (2008) Aib Residues in Peptaibiotics and Synthetic Sequences: Analysis of Nonhelical Conformations. In: Chemistry & Biodiversity, 5 (7). pp. 1238-1262.

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The \alpha-aminoisobutyric (Aib) residue has generally been considered to be a strongly helicogenic residue as evidenced by its ability to promote helical folding in synthetic and natural sequences. Crystal structures of several peptide natural products, peptaibols, have revealed predominantly helical conformations, despite the presence of multiple helix-breaking Pro or Hyp residues. Survey of synthetic Aib-containing peptides shows a preponderance of $3_{10-},\alpha-$ and mixed $3_{10}/\alpha$-helical structures. This review highlights the examples of Aib residues observed in nonhelical conformations, which fall primarily into the polyproline II (PII) and fully extended regions of conformational space. The achiral Aib residue can adopt both left $\alpha_L$ and right $\alpha_R$ handed helical conformations. In sequences containing chiral amino acids, helix termination can occur by means of chiral reversal at an Aib residue, resulting in formation of a Schellman motif. Examples of Aib residues in unusual conformations are illustrated by surveying a database of Aib-containing crystal structures.

Item Type: Journal Article
Publication: Chemistry & Biodiversity
Publisher: John Wiley & Sons, Inc.
Additional Information: Copyright of this article belongs to John Wiley & Sons, Inc.
Keywords: Conformation analysis;Peptaibiotics;alpha-Aminoisobutyric acid (Aib);Schellman motif.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 07 Oct 2008 11:15
Last Modified: 07 Oct 2008 11:15
URI: http://eprints.iisc.ac.in/id/eprint/16130

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