Stuchebrukhov research group           Department of Chemistry           University of California at Davis

The Main Conclusions

* His291 is a probable pump element in CcO

* Kinetic gating mechanism: ET → Fast PT (pumping H⁺) → Slow PT (chemical H⁺)

* Proton pumping path involves: Glu242 → PRDa₃/Arg438 → His291

* 1e^– /1H⁺ pumping stoichiometry

* Lys171B /Asp173B is a likely proton exit site

* Absence of proton leaking is due to energy profile in exit proton channel

A stepwise electron transfer from Cu_A to binuclear center is coupled to proton translocation from Glu242 to His291. [Popovic, Quenneville, Stuchebrukhov, JPC B, 109, 3616 (2005); BBA 1757, 1035, (2006)]

The schematics of the pumping model