Structural and functional studies on model compounds of purple acid phosphatases and catechol oxidases

The synthesis, single crystal X-ray crystallographic, magnetic and electrochemical characterization of eight representative symmetric and unsymmetric complexes as structural model compounds for active sites in PAPs is reported. A mixed valent diiron as well as an iron(III)-zinc(II) complex as models for the active, reduced form of mammalian and plant PAPs, respectively, were synthesized and characterized. Five diiron(III) compounds as structural models for the oxidized uteroferrin-phosphato and -arsenato complex and a model for the oxidized form of PAP from beef spleen are reported. In addition to the structural relevance the catalase and peroxidase activity of one of these model complexes is introduced. Further we summarize our recent research concerning synergistic investigations on catechol oxidase and on synthetic copper coordination complexes. The catechol oxidase is an important type 3 copper protein for the activation of dioxygen. The development of low-molecular weight catalysts should facilitate the oxidation of organic substances by O-2 In particular the reported copper(II) complexes may serve as structural and functional bioinorganic model compounds for the active sites of dioxygen binding and dioxygen activating copper proteins, respectively. These investigations provided a new X-ray crystallographically characterized type of peroxo copper(II) complexes with a mu(4)-(eta(1))(4) coordination mode. (C) 1999 Elsevier Science S.A. All rights reserved.