1v54: Difference between revisions

==Bovine heart cytochrome c oxidase at the fully oxidized state==

== Publication Abstract from PubMed ==

Mitochondrial cytochrome c oxidase plays an essential role in aerobic cellular respiration, reducing dioxygen to water in a process coupled with the pumping of protons across the mitochondrial inner membrane. An aspartate residue, Asp-51, located near the enzyme surface, undergoes a redox-coupled x-ray structural change, which is suggestive of a role for this residue in redox-driven proton pumping. However, functional or mechanistic evidence for the involvement of this residue in proton pumping has not yet been obtained. We report that the Asp-51 --> Asn mutation of the bovine enzyme abolishes its proton-pumping function without impairment of the dioxygen reduction activity. Improved x-ray structures (at 1.8/1.9-A resolution in the fully oxidized/reduced states) show that the net positive charge created upon oxidation of the low-spin heme of the enzyme drives the active proton transport from the interior of the mitochondria to Asp-51 across the enzyme via a water channel and a hydrogen-bond network, located in tandem, and that the enzyme reduction induces proton ejection from the aspartate to the mitochondrial exterior. A peptide bond in the hydrogen-bond network critically inhibits reverse proton transfer through the network. A redox-coupled change in the capacity of the water channel, induced by the hydroxyfarnesylethyl group of the low-spin heme, suggests that the channel functions as an effective proton-collecting region. Infrared results indicate that the conformation of Asp-51 is controlled only by the oxidation state of the low-spin heme. These results indicate that the low-spin heme drives the proton-pumping process.

The low-spin heme of cytochrome c oxidase as the driving element of the proton-pumping process.,Tsukihara T, Shimokata K, Katayama Y, Shimada H, Muramoto K, Aoyama H, Mochizuki M, Shinzawa-Itoh K, Yamashita E, Yao M, Ishimura Y, Yoshikawa S Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15304-9. Epub 2003 Dec 12. PMID:14673090<ref>PMID:14673090</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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*[[Cytochrome c oxidase 3D structures|Cytochrome c oxidase 3D structures]]

<references/>

</StructureSection>

[[Category: Large Structures]]

[[Category: Aoyama H]]

[[Category: Ishimura Y]]

[[Category: Katayama Y]]

[[Category: Mochizuki M]]

[[Category: Muramoto K]]

[[Category: Shimada H]]

[[Category: Shimokata K]]

[[Category: Shinzawa-Itoh K]]

[[Category: Tsukihara T]]

[[Category: Yamashita E]]

[[Category: Yao M]]

[[Category: Yoshikawa S]]