Kinetic trapping of oxygen in cell respiration

Nature. 1996 Mar 21;380(6571):268-70. doi: 10.1038/380268a0.


Cell respiration in eukaryotes is catalysed by mitochondrial enzyme cytochrome c oxidase. In bacteria there are many variants of this enzyme, all of which have a binuclear haem iron-copper centre at which O2 reduction occurs, and a low-spin haem, which serves as the immediate electron donor to this centre. It is essential that the components of the cell respiratory system have a high affinity for oxygen because of the low concentration of dissolved O2 in the tissues; however, the binding of O2 to the respiratory haem-copper oxidases is very weak. This paradox has been attributed to kinetic trapping during fast reaction of O2 bound within the enzyme's binuclear haem iron-copper centre. Our earlier work indicated that electron transfer from the low-spin haem to the oxygen-bound nuclear centre may be necessary for such kinetic oxygen trapping. Here we show that specific decrease of the haem-haem electron transfer rate in the respiratory haem-copper oxidase from Escherichia coli leads to a corresponding decrease in the enzyme's operational steady-state affinity for O2. This demonstrates directly that fast electron transfer between the haem groups is a key process in achieving the high affinity for oxygen in cell respiration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochrome b Group
  • Cytochromes / metabolism
  • Electron Transport
  • Escherichia coli / enzymology
  • Escherichia coli Proteins*
  • Heme / metabolism*
  • Kinetics
  • Oxygen / metabolism*


  • Cytochrome b Group
  • Cytochromes
  • Escherichia coli Proteins
  • cytochrome bo3, E coli
  • cytochrome oo3, E coli
  • Heme
  • Oxygen