GAPDH is susceptible to modification by a wide range of electrophiles, including 4hydroxynonenal and methylglyoxal . Cysteines in the NAD+ binding site are particularly subject to electrophilic modification 100-102 . To determine whether GAPDH is modified during propachlor treatment, we immunoprecipitated Flag GAPDH from lysates following cellular propachlor treatment. GAPDH interactions are interrupted by our stringent RIPA washes, so that Flag GAPDH is prepared with minimal contamination by other proteins (Figure ). In the absence of treatment, we see GAPDH primarily present as the N-terminally acetylated protein, with a smaller population of the glutathione conjugate (Figure ). After propachlor treatment, we see a new base peak at +176 Da, consistent with a single propachlor adduct (Figure ). No evidence of multiple adducts is observed. We further investigated immunoprecipitated Flag GAPDH by digestion and shotgun proteomics, followed by an open adduct search .