Assessing the utility of infrared spectroscopy as a structural diagnostic tool for β-sheets in self-assembling aromatic peptide amphiphiles

Scott Fleming, Pim W. J. M. Frederix, Ivan Ramos Sasselli, Neil T. Hunt, Rein V. Ulijn, Tell Tuttle

Research output: Contribution to journalArticle

80 Citations (Scopus)

Abstract

beta-Sheets are a commonly found structural motif in self-assembling aromatic peptide amphiphiles, and their characteristic "amide I" infrared (IR) absorption bands are routinely used to support the formation of supramolecular structure. In this paper, we assess the utility of IR spectroscopy as a structural diagnostic tool for this class of self-assembling systems. Using 9-fluorene-methyloxycarbonyl dialanine (Fmoc-AA) and the analogous 9-fluorene-methylcarbonyl dialanine (Fmc-AA) as examples, we show that the origin of the band around 1680-1695 cm(-1) in Fourier transform infrared (FTIR) spectra, which was previously assigned to an antiparallel beta-sheet conformation, is in fact absorption of the stacked carbamate group in Fmoc-peptides. IR spectra from C-13-labeled samples support our conclusions. In addition, DFT frequency calculations on small stacks of aromatic peptides help to rationalize these results in terms of the individual vibrational modes.

Original languageEnglish
Pages (from-to)9510-9515
Number of pages6
JournalLangmuir
Volume29
Issue number30
DOIs
Publication statusPublished - 30 Jul 2013

Keywords

  • urethane
  • architecture
  • turbomole
  • phase
  • proteins
  • supramolecular hydrogels
  • molecular design
  • thermodynamic control
  • IR spectroscopy
  • antiparallel

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