Figure 6. Electrospray ionization (ESI) mass spectrometric detection of methylglyoxal (MG)-glutathione (GSH) adducts. A: GSH incubated alone. B: MG incubated alone. C: Incubation of MG (50 μM)+GSH (100 μM) in the absence of glutathione-S-transferase (GST). D: Incubation of MG (50 μM)+GSH (100 μM) in the presence of glutathione-S-transferase (MG+GSH⁺GST). E: Incubation of photooxidized A2E (oxoA2E) only. F: Incubation of GSH with photooxidized A2E and GST (oxoA2E+GSH⁺GST). The m/z 380.1 signal is attributable to the protonated ion [MG/GSH⁺H]+. The molecular ion species m/z 402.1 is attributable to [MG/GSH⁺Na]+ under positive ion mode.