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Partial side chain fluorination influencing amyloid formation

Fluorinated amino acids have been rarely investigated in amyloid forming peptides. This is surprising since they generally show relatively low helix propensities in comparison to their native counterparts and may thus be more suitable for the incorporation into beta sheet rich structures. In order to elucidate the impact of amino acid side chain fluorination on amyloid formation, we have substituted valine residues within solvent exposed regions of a de novo designed coiled coil peptide that is able to undergo a conformational switch to beta-sheet rich amyloid fibrils. We found that these valine residues are responsible for the structural rearrangement, and resolved the internal architecture of peptide strands within the fibrils (Gerling, Biomacromol., 2011). Interestingly, the number of carbon-fluorine bonds present within the side chain has a significant effect on the kinetics of the structural transition into amyloids. Increasing the fluorine content increases the rate of folding. This effect can be explained by the interplay of several factors. Although size and hydrophobicity directly and additively increase with fluorination, α-helical propensity decreases. Thus, the incorporation of fluorinated building blocks into amyloidogenic structures could be of use in materials science applications.