Figure 6: Permeabilization ability of aS-DOPAL oligomers in different membrane models.

(a) Planar Lipid Membrane experiments showing the permeabilization ability of aS-DOPAL oligomers in lipid membranes constituted by POPC/CHO, and relative conductances distribution to characterize the pores formed. The same permeabilization was not present when the planar membranes were prepared with DOPE/DOPG. (b) POPC/CHO SUVs mimicking synaptic vesicles composition and loaded with DA were permeabilized by aS-DOPAL oligomers and allowed the release of DA as measured by monitoring the Tyrosinase dependent Dopachrome formation at 505 nm (blue). When SUVs were not loaded with DA (red) or Tyrosinase was removed from the SUVs solution in the presence of aS-DOPAL oligomers (green), there was no formation of Dopachrome. When only Tyrosinase was added to the DA loaded SUVs (black), a small increase in the measured absorbance was observed probably because of DA leaking. (c) Confocal images of aS-DOPAL oligomers (red) localized at the plasma membrane (green) of BE(2)-M17 cells. (d) Permeabilization of BE(2)-M17 cells by aS-DOPAL oligomers as measured by propidium iodide after 2 and 8 hours treatment. (e) CD measurement of monomeric aS and aS-DOPAL oligomers alone and in the presence or absence of POPC/CHO or DOPE/DOPG SUVs show that aS-DOPAL oligomers can acquire an alpha-helical structure only in the presence of SDS which is able to disaggregate large non-covalent oligomers. (f) AFM images of aS-DOPAL oligomers performed on POPC/CHO lipid monolayer in liquid show that they present the annular shape previously observed by TEM by us and for other aS oligomeric species by others.