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标题：Separate Intramolecular Pathways for Reduction and Oxidation of Cytochrome c in Electron Transport Chain Reactions
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作者：E. Margoliash ; Shelagh Ferguson-Miller ; J. Tulloss 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：11
页码：3245-3249
DOI：10.1073/pnas.70.11.3245
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The monoiodotyrosine 74, formyltryptophan 59, mononitrotyrosine 67, and carboxymethylmethionine 80 derivatives of horse cytochrome c are defective in their ability to accept electrons from the succinate-cytochrome c reductase system, while their reactions with purified cytochrome c oxidase are essentially those of the native protein. The 4-nitrobenzo-2-oxa-1,3-diazole derivative of lysine 13 of horse cytochrome c and the bis-phenylglyoxal derivative of arginine 13 of Candida krusei cytochrome c have the opposite properties, in that they are readily reduced by the succinate-cytochrome c reductase (EC 1.3.99.1 ) system but are defective in their capability of transferring electrons to cytochrome c oxidase (EC 1.9.3.1 ). We conclude that electrons from mitochondrial cytochrome c reductase are transmitted to ferricytochrome c by a different pathway than electrons from ferrocytochrome c to cytochrome c oxidase. The present results are compatible with the concept that the mechanism of reduction involves an aromatic ring channel comprising residues 74, 59, 67, and 80, leading from the "left back" part of the protein to the heme iron. On the other hand, since residue 13 is immediately above the edge of the heme that is at the "front surface" of the molecule, we suggest that the electron leaves ferrocytochrome c to cytochrome c oxidase by way of the edge of pyrrole ring II or the adjacent surface-located sulfur of cysteinyl residue 17, which is thioether bonded to the heme. On this basis, the sites of electron entry and exit in cytochrome c would appear to be some 110{degrees} of arc away from each other along the surface of the protein, explaining several previously observed phenomena.
关键词：monoiodotyrosine 74 cytochrome c ; 4-nitrobenzo-2-oxa-1,3-diazole lysine 13 cytochrome c ; bis-phenylglyoxal arginine 13 cytochrome c