2mp 0132 mass photometer

Mass photometry measurements were performed on a 2MP-0132 mass photometer (Refeyn Ltd). For the measurements, coverslips (No. 1.5 H thickness, 24 × 50 mm, VWR) were cleaned by dipping it into iso-propanol and Milli-Q water followed by drying under a stream of gaseous nitrogen. Subsequently, silicone gaskets (CultureWellTM Reusable Gasket, Grace Bio-Labs) were placed on the cleaned coverslips to create wells for samples. For mass measurements, gaskets were filled with 18 μl protein elution buffer to allow focusing the microscope onto the coverslip surface. Subsequently, 2 μl (50 nM) protein solution was added into the 18 μl droplets and mixed. A movie was recorded for 1 min using the software AcquireMP (Refeyn Ltd). Data analysis was performed using DiscoverMP (Refeyn Ltd). To convert the measured optical reflection-interference contrast into a molecular mass, a known protein size marker (NativeMarkTM Unstained Protein Standard, Invitrogen) was used.

Mass photometry measurements were performed on a 2MP-0132 mass photometer (Refeyn Ltd). For the measurements, coverslips (No. 1.5 H thickness, 24 × 50 mm, VWR) were cleaned by sequential dipping in Milli-Q-water, isopropanol and Milli-Q-water followed by drying under a stream of gaseous nitrogen. Subsequently, silicone gaskets (CultureWell^™ Reusable Gasket, Grace Bio-Labs) were placed on the cleaned coverslips to create wells for sample loading. For mass measurements, gaskets were filled with 18 μl equilibration buffer (50.mM Tris–HCl, pH 7.5 and 100 mM NaCl) to allow focusing the microscope onto the coverslip surface. Subsequently, 2 μl protein solution was added into the 18 μl droplets and mixed to obtain 50–200 nM final protein concentration. Sample binding to the coverslip surface was monitored by recording a movie for 1 minute using AcquireMP (Refeyn Ltd) software. Data analysis was performed using DiscoverMP (Refeyn Ltd). To convert the measured optical reflection-interference contrast into a molecular mass, a known protein size marker (NativeMark^™ Unstained Protein Standard, Invitrogen) was measured.