Figure 3. Dithionite-minus-air oxidized difference spectra of the R. sphaeroides cbb3–type oxygen reductases.
The 551 nm peak is due to hemes c and 561 nm peak is mostly due to the low spin heme b. The data show the absence of the spectroscopic signature for reduced heme b in the E180D, E180Q and E183D mutants.
