Intramolecular Single-Turnover Reaction in a Cytochrome c Oxidase Model Bearing a Tyr244 Mimic

摘要

In the terminal step of respiration, cytochrome c oxidase (CcO) carries out the 4e~- reduction of dioxygen to water. This reaction is coupled to the ATP synthesis, the main energy storage source in the body. In healthy organisms CcO performs without releasing toxic partially reduced oxygen species. Three electrons involved in the reduction originate from the Fe~Ⅱa_3/Cu~Ⅰ active site. The fourth electron and a proton come either from a tyrosine-244 (mixed valence enzyme) or from FeA/CuA (fully reduced enzyme, with proton translocation across the membrane) leading to an oxoferryl-cupric-tyrosyl radical intermediate (P_M) or oxoferryl-cupric intermediate (P_R), respectively.