Extended Data Fig. 5: Identification of 18O-labelled 4-HMA in human cells.
From: The polar oxy-metabolome reveals the 4-hydroxymandelate CoQ10 synthesis pathway
a, Tandem mass spectra (MS2) of homogentisate (HGA) standard, 4-hydroxymandelate (4-HMA) standard, unlabelled (167.0344 m/z) feature precursors, and the respective product fragments. Mass differences between the precursor and product ions reflect loss of one CO2. The red line indicates fragmentation of the precursor ion into the two product ions. The structure of the precursor and product ions are depicted on the left. b, MS2 of unlabelled (167.0344 m/z), +one 18O (169.0387 m/z), and +two 18O (171.0428 m/z) labelled 4-HMA precursors, and the respective product fragments. Mass differences between precursor and product ions reflects loss of unlabelled and +one 18O-labelled CO2. The red line indicates precursor ion fragmentation into two product ions. The structure and position of 18O-labelled (blue and arrow) 4-HMA are depicted on the left. c, d, Total levels of unlabelled and 18O-labelled 4-HMA levels in A498 (c) and SKNDZ (d) cells grown in 3%, 1%, and 0.2% 18O2, and treated with or without IOX1 (dioxygenase inhibitor) for 24 h. n = 3 in biologically independent replicates for each group and condition. Graphs represent mean ± s.e.m. and were compared by two-way ANOVA (c, d), followed by Bonferroni post hoc test (*P < 0.05, ^P < 0.01, %P < 0.005, #P < 0.0001).
