Figure 3.

E4 and SlMsrB2 regulate the redox state of NOR. A, Oxidation of Met in NOR by H₂O₂ led to a mobility shift of the oxidized protein (OX-NOR).B, E4 and SlMsrB2 can reduce Met-SO in OX-NOR in vitro. The oxidation state of peptides containing Met was determined by LC-MS/MS. Each bar represents the mean ± se of three biological replicates. Different letters above the bars indicated statistically significant differences between the samples (Student’s t test; P < 0.01). C, MS analysis of the tryptic fragments of NOR-GFP protein during tomato fruit ripening. Total protein was extracted from the p35S:NOR-GFP transgenic fruit at 55 dpa, and then incubated with GFP-Trap beads for 4 h. The trapped NOR-GFP was digested with trypsin and then analyzed by LC-MS/MS. The peptide containing Met-138 sulfoxidation is shown highlighted in red. The b- and y-ion series are labeled.