Figure 2.

Cytosolic ICDH activity is sensitive to oxidation. 4.38 µM (200 ng/µL) ICDH were incubated with different concentrations of (A) H₂O₂/GSH, (B) nitrosoglutathione (GSNO) or (C) oxidized glutathione (GSSG) for 15 min at 25 °C. This reaction mixture was diluted 250 times in reaction buffer during the assay. ICDH activity was measured for 800 ng of ICDH at 25 °C in 1 mL reaction medium containing 100 mM phosphate buffer (KOH, pH 7.5), 5 mM MgCl2, 250 µM of NADP⁺ and 2.5 mM DL-isocitric acid by monitoring the change in absorbance at 340 nm due to the isocitrate-dependent rate of NADP⁺ reduction. Error bars represent SE (n = 3). * p < 0.05, ** p < 0.01 for statistical differences compared to non-treated samples (Student’s t test).