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Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity
Author(s) -
Gülzow Jana,
Hörner Gerald,
Strauch Peter,
Stritt Anika,
Irran Elisabeth,
Grohmann Andreas
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605868
Subject(s) - deprotonation , chemistry , catechol , ligand (biochemistry) , electron paramagnetic resonance , catalysis , oxygen , stereochemistry , metal , medicinal chemistry , oxidase test , guaiacol , enzyme kinetics , reactivity (psychology) , active site , photochemistry , enzyme , organic chemistry , nuclear magnetic resonance , biochemistry , ion , medicine , physics , receptor , alternative medicine , pathology
Abstract Deprotonation of ligand‐appended alkoxyl groups in mononuclear copper(II) complexes of N,O ligands L 1 and L 2 , gave dinuclear complexes sharing symmetrical Cu 2 O 2 cores. Molecular structures of these mono‐ and binuclear complexes have been characterized by XRD, and their electronic structures by UV/Vis, 1 H NMR, EPR and DFT; moreover, catalytic performance as models of catechol oxidase was studied. The binuclear complexes with anti ‐ferromagnetically coupled copper(II) centers are moderately active in quinone formation from 3,5‐di‐ tert ‐butyl‐catechol under the established conditions of oxygen saturation, but are strongly activated when additional dioxygen is administered during catalytic turnover. This unforeseen and unprecedented effect is attributed to increased maximum reaction rates v max , whereas the substrate affinity K M remains unaffected. Oxygen administration is capable of (partially) removing limitations to turnover caused by product inhibition. Because product inhibition is generally accepted to be a major limitation of catechol oxidase models, we think that our observations will be applicable more widely.