Extended Data Fig. 2: Effect of NaCl on α-Syn LLPS.
From: Mass photometric detection and quantification of nanoscale α-synuclein phase separation
a. Representative fluorescence microscopy images of the spontaneous LLPS regime of α-Syn at 0 mM (left), 110 mM (middle) and 250 mM (right) NaCl concentrations. The experiments are performed in a sealed well-plate setup at 25 °C. The green rectangles indicate samples where macroscopic phase separation is observed. b. Representative fluorescence microscopy images of 200 μM α-Syn + 20% (w/v) PEG samples prepared in 20 mM sodium phosphate buffer, pH 7.4 at increasing (0–500 mM) NaCl concentrations (at 25 °C). Sticking/clumping of droplets without actual merging immediately after their formation is observed at 500 mM NaCl concentration due to altered material properties (more gel-like) (indicated with a white triangular pointer). Therefore, at ≥500 mM NaCl, the phase transition is no longer accurately described as liquid to liquid; but rather as a liquid to gel transition. The experiments (a-b) are performed n = 2 independent times with similar observations. c. (Left) Normalized fluorescence intensity profiles of α-Syn droplets post photobleaching at 200, 400 and 500 mM NaCl concentration are shown. Values represent mean±SD for n = 3 independent experiments. The downward arrow indicates increased solidity of the droplets with increasing NaCl concentration. (Right) Representative fluorescence microscopy images of droplets at 0 s, 10 s and 20 s after photobleaching for samples containing 200, 400 and 500 mM NaCl. The bleached droplets are indicated with white squares. d. Schematic depicting the effect of NaCl on spontaneous α-Syn phase separation. PEG: PEG-8000 unless mentioned otherwise.
