FIGURE 2.

Effect of GSH and GSSG on the sensitivity of cTPI activity to NEM, H₂O₂ and diamide. Recombinant cTPI was incubated without (A) or with (B) 1 mM GSH prior to treatment with NEM (black triangles), H₂O₂ (white circles) or diamide (black circles). Activity (mean ± SE, n = 3) was measured at different time points during the treatment and DTT (10 mM) was added to all samples after 120 min (black arrow). In (C), cTPI was incubated with 1 mM GSH (GSH), 1 mM GSSG (GSSG) or no addition (CTL). Samples were treated with 1 mM diamide and cTPI activity (mean ± SE, n = 3) was measured within 5 min (black bars). After, DTT was added at a final concentration of 10 mM and cTPI activity was measured again after 90 min of incubation (white bars). Data with different letters are significantly different (Student’s t-test, P < 0.05). Activity is expressed as percentage of the control (untreated) sample remaining activity in order to take into account the loss of cTPI activity upon dilution without reductant.