Figure 5.

Mimicking sulfoxidation decreases MaAPX1 activity. MaAPX1-M36Q is a mutated form of MaAPX1 in which Met36 is mutated to glutamine to mimic sulfoxidation, whereas Met36 is mutated to valine in MaAPX1-M36V to mimic the blocking of sulfoxidation. (A,B) Activities of purified recombinant MaAPX1, MaAPX1-M36Q, and MaAPX1-M36V proteins by spectrophotometry (A) and reactive staining (B) methods. (C) The MaAPX1, MaAPX1-M36Q, and MaAPX1-M36V constructs was transformed into Arabidopsis mesophyll protoplasts. After incubation overnight at 22 °C, the protoplasts were collected to analyze APX activity by spectrophotometry. Different letters above the bars indicate statistically significant differences between the samples (Student’s t test; p < 0.05).