Fig. 9: A potential catalytic cycle of CcO based on our results. | Nature Communications

Fig. 9: A potential catalytic cycle of CcO based on our results.

From: Cryo-EM structures of intermediates suggest an alternative catalytic reaction cycle for cytochrome c oxidase

Fig. 9

The classical P-state is an oxygenated oxidized form of CcO. Input of one electron reduces the bound dioxygen to superoxide which remains bound in the BNC near CuB (classical F-state). Input of another electron reduces the superoxide to a peroxide which forms a bridging ligand in the BNC of the O-state. The next input of an electron leads to the formation of the classical E-state whose structure is still unknown. Input of the fourth electron leads to the formation of a 2-electron R-state which binds a dioxygen molecule closing the cycle. Two water molecules or one water molecule plus one hydroxide ion are formed during the input of the third and fourth electrons in the classical reductive phase.

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