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Comment
. 1999 Nov 9;96(23):12971-3.
doi: 10.1073/pnas.96.23.12971.

How oxygen is activated and reduced in respiration

G T Babcock  1
Affiliations
Comment

How oxygen is activated and reduced in respiration

G T Babcock. Proc Natl Acad Sci U S A. .
No abstract available

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Figures

Figure 1
Figure 1
The binuclear center in cytochrome oxidase. Heme a3 and CuB are shown along with the proximal ligand for the heme iron, H376, and the CuB ligand, H240, which is cross-linked to Y244 (24, 25). O2 binding and reduction occurs in the region between the a3 iron and CuB.
Figure 2
Figure 2
A simplified scheme for the reaction between cytochrome oxidase and O2. The binuclear site, which contains heme a3, CuB, and the cross-linked, H240 - Y244 (H-Y) structure, is shown. Reduction and protonation of the oxidized form of the center produces the reduced site. This binds O2 to form initially the oxy species, which reacts further to produce P and F intermediates, before regenerating the oxidized form of the enzyme. The reduction of P and F are limited by proton transfer reactions, as indicated. The steps between P and the reduced form of the site have been implicated in proton pumping processes, which are indicated by red arrows. The stoichiometry of these steps is a matter of current investigation, although up to four protons can be pumped during the complete cycle.
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References

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