Native MS and IM-MS Analysis of Proteins

Native IM-MS of βLG and TTR was performed using a Waters Synapt G2S traveling-wave IM mass spectrometer, and native MS of T80 was performed on a Waters Synapt G1 traveling-wave IM mass spectrometer. Samples were ionized using offline borosilicate emitters (Thermo). The capillary voltage was 1.2 to 1.5 kV, and the cone voltage was 20 V. The source temperature was 25 °C, and the source pressure was 3.4 mbar. Wave height and wave velocity were 35 V and 700 m/s in the IM spectrometry cell and 10 V and 248 m/s in the transfer cell. The IM spectrometry gas was nitrogen with a flow of 50 ml/min, and the trap gas was argon with a flow of 10 ml/min. Mass spectra were processed using MassLynx 4.1 (Waters). IM-MS data were analyzed using PULSAR (version 2.0, 2018) (28 (link)). Drift tube CCS values for βLG and TTR were used to calibrate T-wave data. Theoretical CCS values were computed using projection approximation in IMPACT (29 (link)) and scaled with the empirical factor of 1.14 (30 (link)). Native MS of CTC was performed on a Q-ToF Ultima API mass spectrometer (Waters) equipped with a Z-spray source using offline borosilicate emitters (Thermo). The source temperature was 30 °C, the capillary voltage was 1.5 kV, and the cone voltage was 20 V, respectively. The source pressure was maintained at 7 mbar. The mass spectrometer was operated in single-reflector mode.