Electron Paramagnetic Resonance Studies of Cobalt-Copper Bovine Superoxide Dismutase

1. EPR spectra of cobalt-copper bovine superoxide dismutase at liquid nitrogen and liquid helium temperature show that the two metal centers are magnetically coupled. The temperature dependence of the spectra indicates that this coupling arises from an exchange interaction. 2. The EPR spectrum of th...

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Bibliographic Details
Published in:The Journal of biological chemistry 1974-05, Vol.249 (10), p.3157-3160
Main Authors: Rotilio, Giuseppe, Calabrese, Lilia, Mondovì, Bruno, Blumberg, William E.
Format: Article
Language:English
Subjects:
animal science
Azides
Binding Sites
Cobalt
Cold Temperature
Copper
Cyanides
Electron Spin Resonance Spectroscopy
Ferrocyanides
livestock
Metalloproteins
Oxidation-Reduction
Protein Conformation
Spectrophotometry
Spectrophotometry, Ultraviolet
Superoxide Dismutase
Zinc
zoology
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Summary:1. EPR spectra of cobalt-copper bovine superoxide dismutase at liquid nitrogen and liquid helium temperature show that the two metal centers are magnetically coupled. The temperature dependence of the spectra indicates that this coupling arises from an exchange interaction. 2. The EPR spectrum of the Co(II) of the enzyme can only be seen after reduction of the Cu(II), at very low temperature. It is typical of tetrahedral coordination which is distorted in a particular way. The EPR parameters are g⊥ ≃ 4, g|| ≃ 2, D = 11.5 cm-1. No feature indicating interaction between the two Co(II) centers is observed. 3. Anions such as CN- and N3- do not affect the EPR spectrum of Co(II) significantly, but only modify the spectrum of Cu(II). It is concluded that the Co(II) site (and presumably the native Zn(II) site) can be described as distorted tetrahedral, strongly spin-coupled to the Cu(II) and therefore very near to it, and noninteracting with the other Co(II) site and with solvent molecules.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)42651-3