A Cu(I)-semiquinone state in substrate-reduced amine oxidases

The role of copper in copper-containing amine oxidases has long been a source of debate and uncertainty. Numerous electron paramagnetic resonance (EPR) experiments, including rapid freeze-quench studies, have failed to detect changes in the copper oxidation state in the presence of substrate amines....

Full description

Saved in:
Bibliographic Details
Published in:Nature (London) 1991-01, Vol.349 (6306), p.262-264
Main Authors: Dooley, D M, McGuirl, M A, Brown, D E, Turowski, P N, McIntire, W S, Knowles, P F
Format: Article
Language:English
Subjects:
6-hydroxydopa quinone
Amine Oxidase (Copper-Containing)
Amines
Anaerobic conditions
Anaerobiosis
Arthrobacter
Arthrobacter - enzymology
Biochemistry
Catalysis
Change detection
Chemistry
Copper
copper (I)-semiquinone
copper (II)
Copper - metabolism
Electron paramagnetic resonance
Electron Spin Resonance Spectroscopy
Enzymes
Fabaceae - enzymology
Oxidation
Oxidation-Reduction
Oxidoreductases Acting on CH-NH Group Donors - metabolism
Oxygen
Oxygen - metabolism
Plants, Medicinal
Quinones
Reduction
Reoxidation
Space life sciences
Spectrum analysis
Substrates
Valence
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The role of copper in copper-containing amine oxidases has long been a source of debate and uncertainty. Numerous electron paramagnetic resonance (EPR) experiments, including rapid freeze-quench studies, have failed to detect changes in the copper oxidation state in the presence of substrate amines. One suggestion that copper reduction might occur, has never been confirmed. Copper amine oxidases contain another cofactor, recently identified as 6-hydroxydopa quinone (topa quinone), which is reduced by substrates. Copper has been implicated in the reoxidation of the substrate-reduced enzyme, but the failure to detect any copper redox change has led to proposals that Cu(II) acts as a Lewis acid, that it has an indirect role in catalysis, or that it serves a structural role. We present evidence for the generation of a Cu(I)-semiquinone state by substrate reduction of several amine oxidases under anaerobic conditions, and suggest that the Cu(I)-semiquinone may be the catalytic intermediate that reacts directly with oxygen.
ISSN:0028-0836
1476-4687
DOI:10.1038/349262a0