Extended Data Fig. 2: H3Y99 sulfation is misannotated in HCD MS/MS spectra from Yu et al.’s short proteomic runs.
From: Mass spectrometry and enzyme assays refute histone tyrosine sulfation
AyLVGLFEDTNLC(carbamidomethyl)AIHAK, (y= sulfotyrosine) HCD MS/MS spectra in the HepG2 nuclear extract sample (a), mixed sample (b) and synthetic sulfopeptide sample (c) as shown by Yu et al. The HCD MS/MS spectra annotations suggest b-type ions retaining the SO3. Upon revisiting Yu et al.’s raw data, HCD MS/MS spectra showing a sulfopeptide fragmentation behavior with the complete SO3 neutral loss were observed in the HepG2 nuclear extract sample (d), mixed sample (e) and synthetic sulfopeptide sample (f).
