Extended Data Fig. 5: Characterization of identified CYS fates.
From: Excess cysteine drives conjugate formation and impairs proliferation of NRF2-activated cancer cells
(A) LC–MS metabolomics ion counts of three hypothesized methylglyoxal-derived CYS fates after purified chemical standards of glucose metabolic fates (substrates) were incubated with or without purified cysteine for one hour at 37 °C. n = 2 separate reactions. (B) Proposed chemical structures of hemithioacetal and thiazolidine fates of the reaction between cysteine and methylglyoxal. (C) LC–MS chromatography for isobaric peaks from samples of SSP25 cell extract compared to the product of a cell-free reaction of combining CYS with either dihydroxyacetone phosphate (DHAP) or glyceraldehyde-3-phosphate (G3P) or to a chemical standard of 2-carboxyethyl-L-cysteine. (D) Ion counts measured by LC–MS metabolomics for three sugar-CYS fates and their parent sugar phosphate compounds, from cell-free reaction systems combining increasing molar ratios of CYS with each sugar phosphate. n = 2. (E) Tandem mass spectrometry (MS/MS) fragmentation patterns for the three CYS fates generated in a cell-free system by combining sugar phosphates with CYS compared to the corresponding analytes extracted from SSP25 cells. (F) MS/MS fragmentation patterns for the CYS fate, C191_10.4, generated in a cell-free system by comining pyruvate with CYS compared to the corresponding analyte extracted from SSP25 cells. (G) LC–MS metabolomics ion counts of three hypothesized carbonyl-derived CYS fates after purified chemical standards (substrates) were incubated with or without purified cysteine for one hour. n = 2. (H) MS/MS fragmentation patterns for the three CYS fates generated in a cell-free system by combining the annotated carbonyl metabolites with CYS compared to the corresponding molecules extracted from SSP25 cells.
