FIGURE 2.

Functional analysis of AtAPX1 protein as ascorbate peroxidase and molecular chaperone. (A) The APX activity was monitored by measuring the reduction in absorbance at 290 nm using (◆) 62.5 nM, (◼) 125 nM, (▲) 250 nM, (○) 500 nM, and (●) 0 nM purified AtAPX1 protein. (B) Chaperone activity was measured at 650 nm using malate dehydrogenase (MDH) as a substrate. Thermal aggregation of 1 μM MDH was examined at 43°C for 15 min in the presence of purified AtAPX1 protein in molar ratios of MDH:AtAPX1, (◆) 1:0.25, (◼) 1:0.5, (▲) 1:1, and (○) 1:2. (●) Control indicated the thermal aggregation of MDH in the absence of AtAPX1.