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PolyQ aggregation studied by model peptides with intrinsic tryptophan fluorophores

PolyQ aggregation studied by model peptides with intrinsic tryptophan fluorophores

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SIU, Ho-Wah, Paul STRITT, Heng ZHAO, Karin HAUSER, 2022. PolyQ aggregation studied by model peptides with intrinsic tryptophan fluorophores. In: Biophysical Chemistry. Elsevier. 284, 106782. ISSN 0301-4622. eISSN 1873-4200. Available under: doi: 10.1016/j.bpc.2022.106782

@article{Siu2022-05PolyQ-57036, title={PolyQ aggregation studied by model peptides with intrinsic tryptophan fluorophores}, year={2022}, doi={10.1016/j.bpc.2022.106782}, volume={284}, issn={0301-4622}, journal={Biophysical Chemistry}, author={Siu, Ho-Wah and Stritt, Paul and Zhao, Heng and Hauser, Karin}, note={Article Number: 106782} }

Zhao, Heng Stritt, Paul Siu, Ho-Wah Stritt, Paul eng Polyglutamine (polyQ) model peptides are ideally suited to analyze the involvement of glutamines in the disease-related aggregation onset. Here we use a template-assisted design of polyQ-rich hairpin peptides (Trpzip-Q<sub>n</sub>) to monitor structural stability with fluorescence spectroscopy. The hairpin model imitates the monomeric motif of a polyQ fibril and is stabilized by hydrophobic interactions of two cross-strand pairs of tryptophans (Trps) which are used as fluorophores to report on structural changes. The Trps also frame the polyQ repeats located on each hairpin strand with a different number of glutamines (Q<sub>n</sub>). Single-stranded sequences mimic the unfolded state and were used as references to differentiate the intrinsic fluorescence signal from the spectral effect caused by structural changes. Temperature-induced hairpin unfolding was monitored by the spectral shift of the Trp fluorescence signal and transition temperatures were determined. The magnitude of the spectral shift indicates the degree of structural disorder. We observed that a longer polyQ repeat is more disordered and weakens the cross-strand Trp-Trp interactions resulting in a decrease of the spectral shift. Aggregation to a fibrillar and more ordered structure shows an increase of the spectral shift. In addition, a band at 280 nm occurs in the spectrum which clearly correlates with the turbidity of the sample and is attributed to scattering of larger aggregated structures. Our study reveals that the number of glutamines, pH and temperature affect structural stability and aggregation of polyQ repeats. Hauser, Karin 2022-03-29T09:31:00Z Attribution-NonCommercial-NoDerivatives 4.0 International 2022-05 Siu, Ho-Wah PolyQ aggregation studied by model peptides with intrinsic tryptophan fluorophores 2022-03-29T09:31:00Z Zhao, Heng Hauser, Karin

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