Solution chemical properties and catecholase-like activity of the copper(II)-Ac-His-His-Gly-His-OH system, a relevant functional model for copper containing oxidases.
The solution chemical properties, superoxide dismutase and catecholase activity of the copper(ii)-Ac-His-His-Gly-His-OH (hhgh) complexes were studied to identify functional and structural models of copper-containing oxidases. The solution speciation was determined in the pH range 3-11 by two independent methods (potentiometry and pH-dependent EPR measurements). The results obtained by the two methods agree very well with each other and show the formation of differently protonated CuH(x)L complexes (where x= 2 ,1, 0, -1, -2, -3) in aqueous solution. The spectroscopic (UV-Vis, CD, EPR) data indicate that the coordination of the imidazole rings is a determinant factor in all these complexes. Amide coordinated complexes are dominant only above pH 8. This offers excellent possibilities for structural/functional modelling of copper(ii) containing metalloenzymes. Indeed, the {3N(im)} coordinated CuL species (pH = 6-7) has efficient superoxide dismutase-like activity. The {3N(im),OH(-)} coordinated CuH(-1)L possesses outstanding activity to catalyze the oxidation of 3,5-di-tert-butylcatechol (H(2)dtbc) by dioxygen in 86 wt% methanol-water, providing the first example that copper(ii)-peptide complexes are able to mimic copper containing oxidases.
Jancsó
A
A
Department of Chemistry, University of Turku, FIN-20014 Turku, Finland.
Paksi
Z
Z
Jakab
N
N
Gyurcsik
B
B
Rockenbauer
A
A
Gajda
T
T
D040761:Biomimetic Materials / Q000737:chemistry*; D002396:Catechols / Q000378:metabolism; D003300:Copper / Q000737:chemistry*; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry*; D012996:Solutions
D002396:Catechols; D009842:Oligopeptides; D012996:Solutions; D003300:Copper; D010088:Oxidoreductases; C024748:copper oxidase; C034221:catechol