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Publication Abstract from PubMed

Fully oxidized cytochrome c oxidase (CcO) under enzymatic turnover is capable of pumping protons, while fully oxidized CcO as isolated is not able to do so upon one-electron reduction. The functional difference is expected to be a consequence of structural differences: [Fe(3+)-OH(-)] under enzymatic turnover versus [Fe(3+)-O(2)(2-)-Cu(2+)] for the as-isolated CcO. However, the electron density for O(2)(2-) is equally assignable to Cl(-). An anomalous dispersion analysis was performed in order to conclusively demonstrate the absence of Cl(-) between the Fe(3+) and Cu(2+). Thus, the peroxide moiety receives electron equivalents from cytochrome c without affecting the oxidation states of the metal sites. The metal-site reduction is coupled to the proton pump.

Distinguishing between Cl- and O2(2-) as the bridging element between Fe3+ and Cu2+ in resting-oxidized cytochrome c oxidase.,Suga M, Yano N, Muramoto K, Shinzawa-Itoh K, Maeda T, Yamashita E, Tsukihara T, Yoshikawa S Acta Crystallogr D Biol Crystallogr. 2011 Aug;67(Pt 8):742-4. Epub 2011 Jul 12. PMID:21795816^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.