Peptides from SmE-digested proteins were separated and analyzed using a Dionex UltiMate 3000 high-performance liquid chromatograph (Thermo Fisher Scientific) coupled to an Orbitrap Lumos Fusion mass spectrometer (Thermo Scientific Instruments) modified with an excimer laser (193 nm, 500 Hz) from Coherent, Inc. to enable UVPD in the dual linear ion trap of the instrument. Trap (5 cm length, 3 µm particles, 120 Å pore size, ID 100 µm) and analytical columns (20 cm length, 3 µm particles, 120 Å pore size, ID 75 µm) were packed in-house with UChrom C18 stationary phase (NanoLCMS Solutions, Oroville, CA). 1-4 µL of a 100 ng/µL digest was injected and separated using a gradient consisting of mobile phase A (water with 0.1% formic acid) and mobile phase B (acetonitrile with 0.1% formic acid). Representative LC traces are shown in Figures . MS1 scans were acquired at an Orbitrap resolution of 30,000 at m/z 400. The resolution was set to 60,000, and the AGC target was set to 5E4 for all MS2 spectra. If a precursor subjected to HCD produced an oxonium ion common to O-glycans (i.e. m/z 204.08, 292.10, etc.), and these ions were within the top 20 most abundant ion peaks in the spectrum, then a subsequent UVPD spectrum was acquired for the same precursor using 5 laser pulses of 3 mJ energy. This approach was applied to the top three precursor peaks from each MS1 scan. All data were acquired in triplicate.