Cmos camera

NTA measurements of protein clusters in the dilute phase in equilibrium with condensates, and at a protein concentration below c_sat, were performed using a ZetaView instrument equipped with a CMOS camera and a 405 nm laser (Particle Metrix). The instrument was calibrated according to the manufacturer’s protocol using polystyrene nanoparticle standards. For the analysis of cluster formation below c_sat, samples were prepared at 280 nM protein concentration and low ionic strength (20 mM NaCl), and injected into the sample chamber using a 1 mL syringe until the chamber was completely filled. For the analysis of the dilute phase in equilibrium with the condensates, heterogeneous solutions at 1 µM enzyme concentration were centrifuged at 8000 × g for 30 min to separate the dilute and the dense phase. Subsequently, samples were injected into the chamber using a 1 mL syringe. The chamber was washed with a buffer between two sample measurements until no particles were visible. Video acquisition was performed at 11 different positions with the shutter set to 100 and a high frame rate. The sensitivity was adjusted for each sample to a scattering intensity below 20. More than 1000 traces were analyzed per sample. Data analysis was performed using the ZetaView analysis software (ZetaView 8.04.02 SP2).