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An Interesting Reaction of Cupric Ions with Ferricyanide and Ferrocyanide

  • P. McMahill
  • N. Blackburn
  • H. S. Mason
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 74)

Abstract

The possibility that Cu(III), or cupryl ion [Cu(I)0°], participates in enzymic reactions of copper with dioxygen and other oxidizing substrates, as Dr. Hamilton suggests in the preceeding paper, is an extremely interesting one which opens new vistas of mechanism. However, absolutely unambiguous criteria for the 3+ oxidation level of copper in these processes are required. That is the principal point of this note. Here we show that in the presence of excess ferricyanide ion, the EPR spectrum of Cu2+ ions disappears, and reappears when excess ferrocyanide ion is added. As Dr. Hamilton suggests for galactose oxidase, this may be explicable by the reversible oxidation-reduction of Cu2+ to low spin Cu3+. On the other hand, Cu may form ion pairs with ferricyanide, the magnetic interaction in the pairs broadening the EPR spectrum to indetectability. The addition of (low spin) ferrocyanide would then so dilute the ferricyanide that EPR-detectable Cu2+ -ferrocyanide ion pairs are observed.

Keywords

Magnetic Interaction Oxidation Level Principal Point Copper Protein Paramagnetic Species 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Plenum Press, New York 1976

Authors and Affiliations

  • P. McMahill
    • 1
  • N. Blackburn
    • 1
  • H. S. Mason
    • 1
  1. 1.Department of Biochemistry, School of MedicineUniversity of Oregon Health Sciences CenterPortlandUSA

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