Fig. 5. DT-mediated reduction of cyanomet CtrHbsmonitored by UV-vis spectrophotometry.
In each reaction, spectrawere taken every 30 s for the first 10min, every 2 min for the
following 20 min, and every 5min for the remaining 1.5 h. (a) Reduction of cyanometWT
CtrHb. The reduction progresses over 40 min fromthe blue spectrumto the red spectrum.
Inset: kinetic trace at 431nm; the decrease in signal after 40min (time marked by red vertical
arrow) is attributed to damage by DT. (b) Reduction of cyanomet T111H CtrHb. The
initial response is similar toWT (blue to red spectrum) but occurs within 25 min. An additional
blue shift of the spectrum is distinguished after this first phase (red to orange
spectrum). Inset: kinetic trace at 566 nm to show the biphasic nature of the spectral evolution.
The red and orange arrows mark the time of the red and orange spectra.
(c) Reduction of cyanomet L75H CtrHb. The Soret band shifts to ~426 nm within the
~10-smanualmixing dead time. The reduction progresses over 10min fromthe blue spectrum
to the red spectrum, which is distinct from ferrous L75H CtrHb and corresponds to
crosslinked L75H. Inset: kinetic trace at 426 nm, the decrease in signal after 10 min
(time marked by red vertical arrow) is attributed to damage by DT. Note that only the
first 60 min are shown.