Figure 4.
S-Nitrosylation at Cys-32 enhances APX1 enzyme activity. A, GSNO enhances the enzymatic activity of His-APX1 recombinant protein. Purified His-APX1 recombinant protein was treated with various concentrations of GSNO for 1 h and then assayed for the enzymatic activities. B and C, Analysis of the enzymatic activity of His-APX1 and His-APX1C32S recombinant proteins. The purified recombinant proteins treated with 200 μm GSNO (B) or 100 μm S-nitroso-N-acetylpenicillamine (C) for 1 h were used for the enzymatic analysis. Cont, Control (not treated). D, Analysis of the APX activity of 7-d-old seedlings of the indicated genotypes. The seedlings were treated with 200 μm GSNO for 6 h or not treated (Cont). Transgenic plants were generated in the apx1-2 mutant background (numbers refer to the transgenic lines). Error bars = sd from three independent experiments (biological replicates). Two-tailed Student’s t test: *, P < 0.05; **, P < 0.01; and ***, P < 0.001.