# Role of a two-residue spacer in an \alpha, \beta -didehydrophenylalanine containing hexapeptide: crystal and solution structure of Boc-Val- \bigtriangleup Phe-Leu-Ala- \bigtriangleup Phe-Ala-OMe

Padyana, Anil K and Ramakumar, S and Mathur, Puniti and Jagannathan, NR and Chauhan, VS (2003) Role of a two-residue spacer in an \alpha, \beta -didehydrophenylalanine containing hexapeptide: crystal and solution structure of Boc-Val- \bigtriangleup Phe-Leu-Ala- \bigtriangleup Phe-Ala-OMe. In: Journal of Peptide Science, 9 (1). pp. 54-63.

Full text not available from this repository. (Request a copy)

## Abstract

The peptide $Boc-Val^1- \bigtriangleup Phe^2-Leu^3-Ala^4-\bigtriangleup Phe^5-Ala^6-OMe$ has been examined for the structural consequence of placing a two-residue segment between the \bigtriangleup Phe residues. The peptide is stabilized by four consecutive \beta -turns. The overall conformation of the molecule is a right-handed $3_10-helix$, with average (\phi, \psi) values (-67.7A, -22.7A), unwound at the C-terminus. The $^1H NMR$ results also suggest that the peptide maintains its $3_10-helix$ structure in solution as observed in the crystal state. The crystal structure is stabilized through head-to-tail hydrogen bonds and a repertoire of aromatic interactions laterally directed between adjacent helices, which are antiparallel to each other. The aromatic ring of $\bigtriangleup Phe^5$ forms the hub of multicentred interactions, namely as a donor in aromatic C-H...\pi and aromatic C-H...O-C interactions and as an acceptor in a $CH_3...\pi$ interaction. The present structure uniquely illustrates the unusual capability of a \bigtriangleup Phe ring to host such concerted interactions and suggests its exploitation in introducing long-range interactions in the folding of supersecondary structures.

Item Type: Journal Article The copyright belongs to European Peptide Society and John Wiley & Sons, Ltd. 310 helix;aromatic interactions;constrained peptides; crystal solution structure;de novo design;didehydrophenylalanine Division of Physical & Mathematical Sciences > Physics 12 Jan 2006 27 Aug 2008 11:40 http://eprints.iisc.ernet.in/id/eprint/4985