Fig. 7.

A) Fluorescence intensity difference between 97 μM Na₂S₂-treated (1) PDI-AAAA or (2) PDI-CCCC and untreated (3) PDI-AAAA or (4) PDI-CCCC. SSP4 (5 μM) was incubated with the proteins (5 μM) for 30 min at room temperature in the dark. Results are expressed as mean ± SEM (n = 3). Statistical analyses were performed using one-way ANOVA. ****P < 0.0001, ***P = 0.0001. B) Inhibition of PDI reductase activity by Na₂S₂. PDI (0.2 uM) was incubated with the indicated concentration of Na₂S₂ and assayed for reductase activity using a di-eosin-GSSG assay.