Fig. 4: H/D exchange properties of aSyn in vitro polymorphs.

a–d Residue-specific HD-exchange profiles of different in vitro polymorphs (see text for further details). e Mapping of residue-specific protonation levels of hsAsyn on the structure of the hsAsyn filament (PDB code: 6A6B). The interface to the second filament, which involves A53, is marked. The scale bar indicates protonation levels relative to the minimum protonation level observed for V37-Q99. Residues with signal overlap were excluded from the analysis (shown in white). f Side view of (e). g, h Residue-specific differences in the protonation levels of hsAsyn and lsAsyn in the region from V37 to Q99 (g), mapped in (h) onto the core structure of hsAsyn fibrils (PDB code: 6A6B). Difference values were calculated on the basis of the average protonation levels observed for two independently seeded samples (hsAsyn I/II and lsAsyn I/II, respectively). Error bars represent std. NACore is the most hydrophobic part of the aSyn sequence. The interface between two aSyn filaments as seen in the structure of hsAsyn (PDB code: 6A6B) is marked.