Sc001

The peptide samples were chromatographically separated on an EASY-nLC II system (Thermo Fisher Scientific Inc., Bremen, Germany) with two columns set up: a trap column C18-A1, 2 cm (SC001, Thermo Fisher Scientific, Waltham, MA, USA) and an analytical column PepMap C18, 15 cm × 75 µm, 3 µm particles, and 100 Å pore size (ES800, Thermo Fisher Scientific, Waltham, MA, USA). Samples (4–8 μL) were analyzed with an LTQ Orbitrap XL hybrid mass spectrometer (Thermo Fisher Scientific Inc., Bremen, Germany). MS data were acquired in the data-dependent MS² mode. Data acquisition was controlled by XCalibur 2.1 software (Thermo Fisher Scientific Inc., Bremen, Germany).

LC/MS analysis was performed on processed materials. A Q-Exactive Orbitrap mass spectrometer with a nano-electrospray ion source (Thermo Fisher Scientific, Bremen, Germany) was used for all analyses. Dried materials were dissolved in water containing 0.1% formic acid. Peptides were isolated using an EASY-nLC 1200 system and reversed phase liquid chromatography. The utilized approach was a two-step column separation. The analytical column was a 10 cm EASY-column (SC2003, Thermo Fisher Scientific), whereas the pre-column was a 2 cm EASY-column (SC001, Thermo Fisher Scientific). The peptides were eluted at 250 nL/min across a 90 min linear gradient from 4% to 100% ACN. The mass spectrometer was operated in positive ion mode to acquire a survey mass spectrum with a resolving power of 70,000 and a consecutive high-collision dissociation (HCD) fragmentation spectrum of the 10 most abundant ions [36 (link)].