Reaction of superoxide radical with quinone molecules

Rimma I. Samoilova, Antony R. Crofts, Sergei A. Dikanov

Research output: Contribution to journalArticlepeer-review


When the superoxide radical O 2 ·- is generated on reaction of KO 2 with water in dimethyl sulfoxide, the decay of the radical is dramatically accelerated by inclusion of quinones in the reaction mix. For quinones with no or short hydrophobic tails, the radical product is a semiquinone at much lower yield, likely indicating reduction of quinone by superoxide and loss of most of the semiquinone product by disproportionation. In the presence of ubiquinone-10, a different species (I) is generated, which has the EPR spectrum of superoxide radical. However, pulsed EPR shows spin interaction with protons in fully deuterated solvent, indicating close proximity to the ubinquinone-10. We discuss the nature of species I, and possible roles in the physiological reactions through which ubisemiquinone generates superoxide by reduction of O 2 through bypass reactions in electron transfer chains.

Original languageEnglish (US)
Pages (from-to)11589-11593
Number of pages5
JournalJournal of Physical Chemistry A
Issue number42
StatePublished - Oct 27 2011
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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