Fig. 6

NMR, CD, and surface plasmon resonance studies of α-syn and S100A9 interactions. a 2D ¹H,¹⁵N-HSQC spectra of 77 μM α-syn before (blue) and after (red) titration with up to 2.5 mM S100A9 in 10 mM phosphate buffer, pH 7.4 and at 10 °C. b Ratios of α-syn amide crosspeak intensities measured in the presence (I) and in the absence (I₀) of S100A9, plotted as a function of α-syn amino acid residue numbers. c Far UV CD spectra of α-syn (black) and S100A9 (blue), 6 μM of each protein in 10 mM phosphate buffer, pH 7.4 and 20 °C. d Far UV CD spectrum of 6 μM α-syn alone before (black) and after addition of equimolar S100A9 (red), the signal of S100A9 was subtracted from the CD spectrum of the mixture. e Surface plasmon resonance response upon binding of injected S100A9 to surface-immobilized α-syn plotted as a function of S100A9 concentration