Figure 3.

Stoichiometry of the redox reaction of diatom PRK with DTNB. Overexpressed and purified PRK from O. sinensis (5.7 μm) was oxidized stepwise with DTNB, and the amount of released TNB was monitored spectroscopically at λ = 412 nm (white triangles). In parallel, the activity of the PRK was measured in an enzymatic test (black circles). The data clearly show that two molecules TNB are released per molecule DTNB, indicating that DTNB reacts with two Cys in close proximity by forming a disulfide. The reactions were incubated at 15°C to stabilize the diatom enzyme.