Figure 2.

GSTF9 oxidation has a different impact on the transferase and glutathione peroxidase activity. (A) Bar graphs show the percentage of transferase activity measured in rate constants (k) of GSTF9_red and GSTF9_ox (0.2 µM), where the GST catalysed conjugation of GSH (0.5 mM) onto CDNB (3.8 mM) is followed at 340 nm. When oxidized, GSTF9_ox activity significantly (P < 0.001) decreases from 100% (0.54 s⁻¹) to 70% (0.38 s⁻¹). MsrA and MsrB treatment causes activity increase from 70% to 94% (0.51 s⁻¹), indicating that Msr enzymes are capable of recovering GSTF9_ox activity. Two control samples were used: GSTF9_ox incubated with DTT and GSTF9_red incubated with MsrA, MsrB and DTT. The data from at least 3 independent experiments are presented as a mean ± SD. (B) FOX assay was used to compare the peroxidase activity of GSTF9_red and GSTF9_ox in the presence of 150 µM H₂O₂. Remained H₂O₂ concentrations were determined for samples taken after 15 and 30 min. Upon treatment of GSTF9 with hydrogen peroxide (GSTF9_ox), glutathione peroxidase activity is not influenced. As a control, the influence of GSH on H₂O₂ reduction was also recorded. The data from 3 independent experiments were normalized and presented as a mean ± SD.