title: Amyloid-derived peptide forms self-assembled monolayers on gold nanoparticle with a curvature-dependent β-sheet structure.
abstract: Using a combination of Fourier transform infrared (FTIR) spectroscopy and solid-state nuclear magnetic resonance (SSNMR) techniques, the secondary structure of peptides anchored on gold nanoparticles of different sizes is investigated. The structure of the well-studied CALNN-capped nanoparticles is compared to the structure of nanoparticles capped with a new cysteine-terminated peptide, CFGAILSS. The design of that peptide is derived from the minimal amyloidogenic sequence FGAIL of the human islet polypeptide amylin. We demonstrate that CFGAILSS forms extended fibrils in solution. When constrained at a nanoparticle surface, CFGAILSS adopts a secondary structure markedly different from CALNN. Taking into account the surface selection rules, the FTIR spectra of CFGAILSS-capped gold nanoparticles indicate the formation of β-sheets which are more prominent for 25 nm diameter nanoparticles than for 5 nm nanoparticles. No intermolecular (13)C-(13)C dipolar coupling is detected with rotational resonance SSNMR for CALNN-capped nanoparticles, while CALNN is in a random coil configuration. Coupling is detected for CFGAILSS-capped gold nanoparticles, however, consistent with an intermolecular (13)C-(13)C distance of 5.0 ± 0.3 Å, in agreement with intermolecular hydrogen bonding in a parallel β-sheet structure.
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Shaw
authors.forename: David A
authors.initials: DA
authors.lastname: Middleton
authors.forename: Martin
authors.initials: M
authors.lastname: Volk
authors.forename: Raphaël
authors.initials: R
authors.lastname: Lévy
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010446:Peptide Fragments / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D000682:Amyloid; D010446:Peptide Fragments; D014867:Water; D006046:Gold