Succinate Dehydrogenase Activity Measurement

Mitochondria were isolated according to the protocol previously described [30 (link)]. The SDH activity was determined using the Succinate Dehydrogenase Activity Colorimetric Assay Kit (Sigma–Aldrich Inc., St. Louis, MO, USA). It was measured by monitoring the decrease in absorbance at 600 nm for 10 min in the presence of 0.1 M sodium succinate (pH 7.5), 0.05 mM 2,6-dichlorophenolindophenol, 0.1 M NaPO₄ buffer (pH 7), and 50–100 μg of resuspended biological membranes in a 1 mL reaction volume. SDH activity was expressed relative to the background reduction of 2,6-dichlorophenolindophenol (membranes without succinate).