FIGURE 4.

Optical spectra of TDO. A, Soret bands of ferric and ferrous CmTDO (5 μm) in the presence of l-Trp (5 mm) are observed at 406 and 432 nm, respectively. The Soret band of the ferric sample splits into two parts 30 s after addition of H₂O₂ (30 μm). B, ferric TDO (black), after sequential addition of l-Trp (red), CO (green), and H₂O₂ (blue). The red and green traces are nearly identical to each other. C, optical spectra of TDO and l-Trp taken from the sequential additions of equal amount of H₂O₂ (see text for experiment details). The inset is the calculated NFK concentration as a function of the added H₂O₂ under anaerobic conditions. The concentration of H₂O₂ was determined using ϵ_{240 nm} = 43.6 m⁻¹ cm⁻¹. NFK concentration was determined using ϵ_{321 nm} = 3150 m⁻¹ cm⁻¹ after subtraction of the initial spectrum.