Foldamers of β-peptides: Conformational preference of peptides formed by rigid building blocks. the first MI-IR spectra of a triamide nanosystem

Gábor Pohl, Esther Gorrea, Vicenç Branchadell, Rosa M. Ortuño, András Perczel, György Tarczay

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

To determine local chirality driven conformational preferences of small aminocyclobutane-1-carboxylic acid derivatives, X-(ACBA) n -Y, their matrix-isolation IR spectra were recorded and analyzed. For the very first time model systems of this kind were deposited in a frozen (∼10 K) noble gas matrix to reduce line width and thus, the recorded sharp vibrational lines were analyzed in details. For cis-(S,R)-1 monomer two "zigzag" conformers composed of either a six or an eight-membered H-bonded pseudo ring was identified. For trans-(S,S)-2 stereoisomer a zigzag of an eight-membered pseudo ring and a helical building unit were determined. Both findings are fully consistent with our computational results, even though the relative conformational ratios were found to vary with respect to measurements. For the dimers (S,R,S,S)-3 and (S,S,S,R)-4 as many as four different cis,trans and three different trans,cis conformers were localized in their matrix-isolation IR (MI-IR) spectra. These foldamers not only agree with the previous computational and NMR results, but also unambiguously show for the first time the presence of a structure made of a cis,trans conformer which links a "zigzag" and a helical foldamer via a bifurcated H-bond. The present work underlines the importance of MI-IR spectroscopy, applied for the first time for triamides to analyze the conformational pool of small biomolecules. We have shown that the local chirality of a β-amino acid can fully control its backbone folding preferences. Unlike proteogenic α-peptides, β- and especially (ACBA) n type oligopeptides could thus be used to rationally design and influence foldamer's structural preferences.

Original languageEnglish
Pages (from-to)957-973
Number of pages17
JournalAmino Acids
Volume45
Issue number4
DOIs
Publication statusPublished - Jul 17 2013

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Keywords

  • Conformational analysis
  • Matrix-isolation IR spectroscopy
  • Peptide folding
  • Synthetic biopolymers
  • β-peptides

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Organic Chemistry

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