Figure 1. Selenite impairs glutaminolysis and blocks the synthesis of downstream metabolites in A549 cells.

A) 1D ¹H NMR spectra were recorded from polar extracts of A549 cells treated for 24 h with 6.25 μM Na₂SeO₃. Spectra were superimposed and normalized to total protein to assess differences between treatments in the intensities of the C-4-Gln and C-4-Glu peaks at 2.44 and 2.34 ppm, respectively. B) The C4-Glu and Gln peaks were quantified and normalized to total protein. ***q<0.001, ** q<0.01. C) Total Gln and Glu normalized to total protein were obtained from GC-MS analysis of polar extracts recorded at 0, 1.5, 3, 6, and 24 h of selenite treatment. D) 1D ¹H{¹³C} HSQC spectra were recorded from polar extracts of A549 cells pre-incubated for 2 hours with ¹³C₅,¹⁵N₂-Gln tracer and treated with or without 6.25 μM Na₂SeO₃ for 0, 1.5, 3, 6, 11, and 24 hours. Control and selenite spectra were superimposed and normalized to total protein to visualize differences between treatments in ¹³C-4-glutathione, ¹³C-4-Gln, and ¹³C-4-Glu at 2.54, 2.44, and 2.34 ppm, respectively. E) GC-MS data were acquired from these extracts and ¹³C₅,¹⁵N₁-Glu (m+6), ¹³C₄-malate, ¹³C₄-fumarate, and ¹³C₄,¹⁵N₁-Asp (m+5) were quantified and normalized to total protein.