Construction of Non-heme Metalloenzyme Model Complexes with Binding and/or Activation Function for Oxygen Species and Their Regulation

点击翻译按钮获取中文摘要

In order to construct non-heme metallo-enzyme model complexes with binding and/or activation function for oxygen species, we prepared some newly-designed metal complexes on the basis of the structures around the active centers for metalloenzymes. The design concept of our original complexes is that the metal active center is surrounded by some non-covalent interaction sites such as hydrogen bonding and hydrophobic interaction groups as the acitve oxygen coordination or substrate-recognition site. Using these metal complexes, we succeeded in obtaining some interesting, important results as follows. (i)As a model of dopamine β-hydroxylase, stable hydroperoxo copper(II) complex was first prepared, whose higher stability was achieved by the hydrogen bonding and hydrophobic interaction groups. And we also succeeded in activation of hydroperoxide ion using unique square-planar copper(II) complex, which exhibited the highest catalytic activity among the hydroperoxo copper complexes prepared hitherto. (ii) We succeeded in preparation of hemerythrin model complexes showing reversible oxygenation function. On the basis of this experiment, it was also found out that the proton transfer from hydroxo to superoxo that appeared in hemerythrin is carried out by mediation of water molecules. (iii)As the methane monooxygenase model, high valence bis-μ-oxo dicopper(III) complex was prepared using newly-designed tridentate ligand, which exhibited higher oxidation activity to oxidize the saturated hydrocarbon compounds to the hydroxyl ones. (iv) We also succeeded in preparation of high valence bus-μ-ox dicopper(III) complex with highly-distorted tetrahedron structure using natural compound spartein. The results (iii) and (iv) include important fact that the dioxygen molecule has been reduced by four electrons from metal ions, which is the basic principle for the fuel cell