Aggregation kinetics of α-synuclein (0.75 mg/ml, 50 μM, circle), tau (1.5 mg/ml, 30 μM, ×), and mixtures of α-synuclein and tau (50 μM and 15 μM, 1:0.3, square; 50 μM and 30 μM, 1:0.6, triangle). Optical density (O. D.) was measured at 400 nm for turbidity of the samples. The accelerated aggregation kinetics was also observed at different protein concentrations (70 μM and 20 μM for α-synuclein and tau, respectively).