The proton pumping pathway of bovine heart cytochrome c oxidase

Kunitoshi Shimokata, Yukie Katayama, Haruka Murayama, Makoto Suematsu, Tomitake Tsukihara, Kazumasa Muramoto, Hiroshi Aoyama, Shinya Yoshikawa, Hideo Shimada

研究成果: Article査読

117 被引用数 (Scopus)


X-ray structures of bovine heart cytochrome c oxidase have suggested that the enzyme, which reduces O2 in a process coupled with a proton pumping process, contains a proton pumping pathway (H-pathway) composed of a hydrogen bond network and a water channel located in tandem across the enzyme. The hydrogen bond network includes the peptide bond between Tyr-440 and Ser-441, which could facilitate unidirectional proton transfer. Replacement of a possible proton-ejecting aspartate (Asp-51) at one end of the H-pathway with asparagine, using a stable bovine gene expression system, abolishes the proton pumping activity without influencing the O2 reduction function. Blockage of either the water channel by a double mutation (Val386Leu and Met390Trp) or proton transfer through the peptide by a Ser441Pro mutation was found to abolish the proton pumping activity without impairment of the O 2 reduction activity. These results significantly strengthen the proposal that H-pathway is involved in proton pumping.

ジャーナルProceedings of the National Academy of Sciences of the United States of America
出版ステータスPublished - 2007 3月 6

ASJC Scopus subject areas

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