Alignment of a model amyloid peptide fragment in bulk and at a solid surface

Ian W. Hamley, Valeria Castelletto, Claire M. Moulton, José Rodríguez-pérez, Adam M. Squires, Tugce Eralp, Georg Held, Matthew R. Hicks, Alison Rodger

Research output: Contribution to journalArticle

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Abstract

The alignment of model amyloid peptide YYKLVFFC is investigated in bulk and at a solid surface using a range of spectroscopic methods employing polarized radiation. The peptide is based on a core sequence of the amyloid β (Aβ) peptide, KLVFF. The attached tyrosine and cysteine units are exploited to yield information on alignment and possible formation of disulfide or dityrosine links. Polarized Raman spectroscopy on aligned stalks provides information on tyrosine orientation, which complements data from linear dichroism (LD) on aqueous solutions subjected to shear in a Couette cell. LD provides a detailed picture of alignment of peptide strands and aromatic residues and was also used to probe the kinetics of self-assembly. This suggests initial association of phenylalanine residues, followed by subsequent registry of strands and orientation of tyrosine residues. X-ray diffraction (XRD) data from aligned stalks is used to extract orientational order parameters from the 0.48 nm reflection in the cross-β pattern, from which an orientational distribution function is obtained. X-ray diffraction on solutions subject to capillary flow confirmed orientation in situ at the level of the cross-β pattern. The information on fibril and tyrosine orientation from polarized Raman spectroscopy is compared with results from NEXAFS experiments on samples prepared as films on silicon. This indicates fibrils are aligned parallel to the surface, with phenyl ring normals perpendicular to the surface. Possible disulfide bridging leading to peptide dimer formation was excluded by Raman spectroscopy, whereas dityrosine formation was probed by fluorescence experiments and was found not to occur except under alkaline conditions. Congo red binding was found not to influence the cross-β XRD pattern.
Original languageEnglish
Pages (from-to)8244-8254
JournalJournal of Physical Chemistry B
Volume114
Issue number24
DOIs
Publication statusPublished - 24 Jun 2010

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Peptides
Raman spectroscopy
Dichroism
X ray diffraction
Capillary flow
Dimers
Self assembly
Diffraction patterns
Distribution functions
Experiments
Fluorescence
Amyloid
Radiation
Silicon
Kinetics

Cite this

Hamley, I. W., Castelletto, V., Moulton, C. M., Rodríguez-pérez, J., Squires, A. M., Eralp, T., ... Rodger, A. (2010). Alignment of a model amyloid peptide fragment in bulk and at a solid surface. Journal of Physical Chemistry B, 114(24), 8244-8254. https://doi.org/10.1021/jp101374e

Alignment of a model amyloid peptide fragment in bulk and at a solid surface. / Hamley, Ian W.; Castelletto, Valeria; Moulton, Claire M.; Rodríguez-pérez, José; Squires, Adam M.; Eralp, Tugce; Held, Georg; Hicks, Matthew R.; Rodger, Alison.

In: Journal of Physical Chemistry B, Vol. 114, No. 24, 24.06.2010, p. 8244-8254.

Research output: Contribution to journalArticle

Hamley, IW, Castelletto, V, Moulton, CM, Rodríguez-pérez, J, Squires, AM, Eralp, T, Held, G, Hicks, MR & Rodger, A 2010, 'Alignment of a model amyloid peptide fragment in bulk and at a solid surface', Journal of Physical Chemistry B, vol. 114, no. 24, pp. 8244-8254. https://doi.org/10.1021/jp101374e
Hamley IW, Castelletto V, Moulton CM, Rodríguez-pérez J, Squires AM, Eralp T et al. Alignment of a model amyloid peptide fragment in bulk and at a solid surface. Journal of Physical Chemistry B. 2010 Jun 24;114(24):8244-8254. https://doi.org/10.1021/jp101374e
Hamley, Ian W. ; Castelletto, Valeria ; Moulton, Claire M. ; Rodríguez-pérez, José ; Squires, Adam M. ; Eralp, Tugce ; Held, Georg ; Hicks, Matthew R. ; Rodger, Alison. / Alignment of a model amyloid peptide fragment in bulk and at a solid surface. In: Journal of Physical Chemistry B. 2010 ; Vol. 114, No. 24. pp. 8244-8254.
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