Kitagishi Hiroaki, Shimoji Daiki, Ohta Takehiro, Kamiya Ryo, Kudo Yasuhiro, Onoda Akira, Hayashi Takashi, Weiss Jean, Wytko Jennifer A, Kano Koji
Department of Molecular Chemistry and Biochemistry , Faculty of Science and Engineering , Doshisha University , Kyotanabe , Kyoto 610-0321 , Japan . Email:
Picobiology Institute , Graduate School of Life Science , University of Hyogo , RSC-UH LP Center , Hyogo 679-5148 , Japan.
Chem Sci. 2018 Jan 15;9(7):1989-1995. doi: 10.1039/c7sc04732k. eCollection 2018 Feb 21.
In mitochondria, cytochrome oxidase (CO) catalyses the reduction of oxygen (O) to water by using a heme/copper hetero-binuclear active site. Here we report a highly efficient supramolecular approach for the construction of a water-soluble biomimetic model for the active site of CO. A tridentate copper(ii) complex was fixed onto 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(iii) (FeTPPS) through supramolecular complexation between FeTPPS and a per--methylated β-cyclodextrin dimer linked by a (2,2':6',2''-terpyridyl)copper(ii) complex (CuTerpyCD). The reduced FeTPPS/CuTerpyCD complex reacted with O in an aqueous solution at pH 7 and 25 °C to form a superoxo-type Fe-O/Cu complex in a manner similar to CO. The pH-dependent autoxidation of the O complex suggests that water molecules gathered at the distal Cu site are possibly involved in the Fe-O/Cu superoxo complex in an aqueous solution. Electrochemical analysis using a rotating disk electrode demonstrated the role of the FeTPPS/CuTerpyCD hetero-binuclear structure in the catalytic O reduction reaction.
在线粒体中，细胞色素氧化酶（CO）利用一个血红素/铜异双核活性位点催化氧气（O）还原为水。在此，我们报道了一种高效的超分子方法，用于构建CO活性位点的水溶性仿生模型。通过5,10,15,20-四（4-磺基苯基）卟吩铁（III）（FeTPPS）与由（2,2':6',2''-三联吡啶）铜（II）配合物（CuTerpyCD）连接的全甲基化β-环糊精二聚体之间的超分子络合作用，将一种三齿铜（II）配合物固定在FeTPPS上。还原后的FeTPPS/CuTerpyCD配合物在pH为7、温度为25℃的水溶液中与O反应，以类似于CO的方式形成一种超氧型Fe-O/Cu配合物。O配合物的pH依赖性自氧化表明，聚集在远端铜位点的水分子可能参与了水溶液中Fe-O/Cu超氧配合物的形成。使用旋转圆盘电极进行的电化学分析证明了FeTPPS/CuTerpyCD异双核结构在催化O还原反应中的作用。
