Spectral characteristics of the mechanism of oxidase activity of ceruloplasmin

The absorbance and EPR spectra of type 1 and 2 copper-binding centres which are present in ceruloplasmin (Cp) molecule were shown to disappear upon the reduction of the enzyme by ascorbate under anaerobic conditions. The fluorescence band attributed to type 3 Cu was altered concomitantly. The electr...

Full description

Saved in:
Bibliographic Details
Published inBiokhimiia (Moscow, Russia) Vol. 53; no. 4; p. 620
Main Authors Vasil'ev, V B, Neĭfakh, S A, Rusakov, D V, Iakovleva, T Iu, Kholmogorov, V E
Format Journal Article
LanguageRussian
Published Russia (Federation) 01.04.1988
Subjects
Ascorbic Acid - metabolism
Binding Sites
Ceruloplasmin - metabolism
Copper - metabolism
Electron Spin Resonance Spectroscopy
Electron Transport
Free Radicals
Luminescent Measurements
Oxidation-Reduction
Oxidoreductases
Spectrum Analysis
Online AccessGet more information

Cover

More Information
Summary:The absorbance and EPR spectra of type 1 and 2 copper-binding centres which are present in ceruloplasmin (Cp) molecule were shown to disappear upon the reduction of the enzyme by ascorbate under anaerobic conditions. The fluorescence band attributed to type 3 Cu was altered concomitantly. The electron-accepting nitroxyl radical added to reduced Cp restored the absorbance, EPR and fluorescence spectra of the oxidase. Only type 1 and 3 copper ions, as judged by spectral changes, can be reduced by ascorbate and then reoxidized by the nitroxyl radical in the azide-treated Cp. The spectral properties of Cp provided by copper ions of different types change simultaneously and concordantly upon oxidation/reduction. This seems to be caused by cooperative interaction of these ions involved in the electron transfer from the donating substrate to the accepting molecule of the nitroxyl radical (in model studies of oxidase reaction) or oxygen (under natural conditions). The copper ions in the active centre of Cp constitute an intramolecular electron transport chain, which may, at least in vitro, function without one of its links.
ISSN:0320-9725