Fig. 3.

Absorbance changes after light-induced dissociation of CO from reduced ba₃ CytcO. The increase in absorbance at 445 nm after the laser flash at t = 0 is associated with dissociation of the CO ligand. The rapid decrease in absorbance is associated with release of CO from Cu_B, whereas the slower decrease in absorbance is associated with recombination of the CO ligand with heme a₃. Experimental conditions: ∼6 µM CytcO in 100 mM Hepes (pH 7.4), 0.05% DDM, 0.1 mM EDTA; 200 µM dithionite (added to the sample after removal of O₂).