Aggregation modes in sheets formed by protected $ {\beta}$ -aminoacids and ${\beta}$-peptides

Sengupta, Anindita and Rituparna S, Roy and Sabareesh, Varatharajan and Narayanaswamy, Shamala and Padmanabhan, Balaram (2006) Aggregation modes in sheets formed by protected $ {\beta}$ -aminoacids and ${\beta}$-peptides. In: Organic & Biomolecular Chemistry, 4 (6). pp. 1166-1173.

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Abstract

The crystal structures of four protected ${\beta}$-amino acid residues,Boc-(S)-${\beta}{^3}$-HAla-NHMe(1);Boc-(R)-${\beta}{^3}$-HVal-NHMe(2);Boc-(S)-${\beta}{^3}$-HPhe-NHMe(3);Boc-(S)-${\beta}{^3}$-HPro-OH(6) and two ${\beta}$-dipeptides,Boc-(R)-${\beta}{^3}$-HVal-(R)-${\beta}{^3}$-HVal-OMe(4);Boc-(R)-${\beta}{^3}$-HVal-(S)-${\beta}{^3}$ HVal-OMe(5) have been determined. Gauche conformations about the $C{^\beta}$ –$C{^\alpha}$ bonds$(\theta{\sim}{\pm}60){^o}$ are observed for the ${\beta}{^3}$-HPhe residues in 3 and all four ${\beta}{^3}$-HVal residues in the dipeptides 4 and 5. Trans conformations $(\theta{\sim}180{^0})$ are observed for ${\beta}{^3}$-HAla residues in both independent molecules in 1 and for the ${\beta}{^3}$-HVal and ${\beta}{^3}$-HPro residues in 2 and 6, respectively. In the cases of compounds 1–5, molecules associate in the crystals via intermolecular backbone hydrogen bonds leading to the formation of sheets. The polar strands formed by ${\beta}{^3}$-residues aggregate in both parallel(1, 3, 5) and antiparallel (2, 4) fashion. Sheet formation accommodates both the trans and gauche conformations about the $C{^\beta}$-$C{^\alpha}$ bonds.

Item Type:	Journal Article
Publication:	Organic & Biomolecular Chemistry
Publisher:	Royal Society of Chemistry
Additional Information:	Copyright of this article belongs to Royal Society of Chemistry.
Keywords:	Chemistry,Organic; Alpha-Amino;Secondary Structure;Hybrid Peptides;Hairpin;Foldamers;Sequences;Residues;Spectroscopy;Hexapeptide;Segments
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	03 Dec 2008 07:01
Last Modified:	19 Sep 2010 04:53
URI:	http://eprints.iisc.ac.in/id/eprint/16723

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