Abstract
Synchrotron X-ray scattering was performed on an aqueous solution containing self-assembled aggregates of a β-sheet-forming peptide conjugated with a water-soluble moiety (polyethylene glycol, PEG or an oligo-peptide comprising a transactivator of transcription, TAT, sequence). The angular dependence of the scattering intensity in the low-q region (that is, q<2.0 nm−1, where q is the magnitude of the scattering vector) indicated that the scattering objects were rod-like and completely dispersed in water without undergoing secondary aggregation. From the scattering intensity in the range of 0.5 nm−1<q<5.0 nm−1, it was deduced that the cross-section of the scattering objects was rectangular and not circular, presumably because of the laminated structure of the β-sheets. In the wide-angle region (that is, q<5.0 nm−1), a diffraction peak was observed at q=13.4 nm−1, which could be assigned to the two neighboring α-carbons of the peptide chains of the cross-section of the β-sheet. The scattering data indicated that the β-sheet-forming peptide indeed formed stacked β-sheets in a manner similar to that observed in the case of amyloid protofilaments, and that the resultant rod-like objects could be completely dispersed in water as a result of the hydrophilic PEG or TAT moiety.
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Acknowledgements
All the SAXS and WAXS measurements were performed at the SPring-8 facility, Japan (2013A1207, 2013B1203). This work was supported by the Photon and Quantum Basic Research Coordinated Development Program of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan and by the Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan.
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Minami, T., Matsumoto, S., Sanada, Y. et al. Rod-like architecture and cross-sectional structure of an amyloid protofilament-like peptide supermolecule in aqueous solution. Polym J 48, 197–202 (2016). https://doi.org/10.1038/pj.2015.97
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DOI: https://doi.org/10.1038/pj.2015.97