View source for 2eik

[[Image:2eik.jpg|left|200px]]<br /><applet load="2eik" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="2eik, resolution 2.10&Aring;" />
'''Cadmium ion binding structure of bovine heart cytochrome C oxidase in the fully reduced state'''<br />

==Overview==
Cytochrome c oxidase transfers electrons and protons for dioxygen, reduction coupled with proton pumping. These electron and proton transfers, are tightly coupled with each other for the effective energy transduction, by various unknown mechanisms. Here, we report a coupling mechanism by a, histidine (His-503) at the entrance of a proton transfer pathway to the, dioxygen reduction site (D-pathway) of bovine heart cytochrome c oxidase., In the reduced state, a water molecule is fixed by hydrogen bonds between, His-503 and Asp-91 of the D-pathway and is linked via two water arrays, extending to the molecular surface. The microenvironment of Asp-91 appears, in the x-ray structure to have a proton affinity as high as that of, His-503. Thus, Asp-91 and His-503 cooperatively trap, on the fixed water, molecule, the proton that is transferred through the water arrays from the, molecular surface. On oxidation, the His-503 imidazole plane rotates by, 180 degrees to break the hydrogen bond to the protonated water and, releases the proton to Asp-91. On reduction, Asp-91 donates the proton to, the dioxygen reduction site through the D-pathway. The proton collection, controlled by His-503 was confirmed by partial electron transfer, inhibition by binding of Zn2+ and Cd2+ to His-503 in the x-ray structures., The estimated Kd for Zn2+ binding to His-503 in the x-ray structure is, consistent with the reported Kd for complete proton-pumping inhibition by, Zn2+ [Kannt A, Ostermann T, Muller H, Ruitenberg M (2001) FEBS Lett, 503:142-146]. These results suggest that His-503 couples the proton, transfer for dioxygen reduction with the proton pumping.

==About this Structure==
2EIK is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=DMU:'>DMU</scene>, <scene name='pdbligand=CU:'>CU</scene>, <scene name='pdbligand=ZN:'>ZN</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=NA:'>NA</scene>, <scene name='pdbligand=CD:'>CD</scene>, <scene name='pdbligand=HEA:'>HEA</scene>, <scene name='pdbligand=CUA:'>CUA</scene>, <scene name='pdbligand=TGL:'>TGL</scene>, <scene name='pdbligand=PGV:'>PGV</scene>, <scene name='pdbligand=CHD:'>CHD</scene>, <scene name='pdbligand=PSC:'>PSC</scene>, <scene name='pdbligand=PEK:'>PEK</scene> and <scene name='pdbligand=CDL:'>CDL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_oxidase Cytochrome-c oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.9.3.1 1.9.3.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2EIK OCA]. 

==Reference==
A histidine residue acting as a controlling site for dioxygen reduction and proton pumping by cytochrome c oxidase., Muramoto K, Hirata K, Shinzawa-Itoh K, Yoko-o S, Yamashita E, Aoyama H, Tsukihara T, Yoshikawa S, Proc Natl Acad Sci U S A. 2007 May 8;104(19):7881-6. Epub 2007 Apr 30. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17470809 17470809]
[[Category: Bos taurus]]
[[Category: Cytochrome-c oxidase]]
[[Category: Protein complex]]
[[Category: Aoyama, H.]]
[[Category: Hirata, K.]]
[[Category: Muramoto, K.]]
[[Category: Shinzawa-Itoh, K.]]
[[Category: Tsukihara, T.]]
[[Category: Yamashita, E.]]
[[Category: Yoko-O, S.]]
[[Category: Yoshikawa, S.]]
[[Category: CD]]
[[Category: CDL]]
[[Category: CHD]]
[[Category: CU]]
[[Category: CUA]]
[[Category: DMU]]
[[Category: HEA]]
[[Category: MG]]
[[Category: NA]]
[[Category: PEK]]
[[Category: PGV]]
[[Category: PSC]]
[[Category: TGL]]
[[Category: ZN]]
[[Category: oxidoreductase]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 15:06:00 2008''