The radical chemistry of galactose oxidase

James W. Whittaker

Research output: Contribution to journalShort surveypeer-review

157 Scopus citations


Galactose oxidase is a free radical metalloenzyme containing a novel metalloradical complex, comprised of a protein radical coordinated to a copper ion in the active site. The unusually stable protein radical is formed from the redox-active side chain of a cross-linked tyrosine residue (Tyr-Cys). Biochemical studies on galactose oxidase have revealed a new class of oxidation mechanisms based on this free radical coupled-copper catalytic motif, defining an emerging family of enzymes, the radical-copper oxidases. Isotope kinetics and substrate reaction profiling have provided insight into the elementary steps of substrate oxidation in these enzymes, complementing structural studies on their active site. Galactose oxidase is remarkable in the extent to which free radicals are involved in all aspects of the enzyme function: serving as a key feature of the active site structure, defining the characteristic reactivity of the complex, and directing the biogenesis of the Tyr-Cys cofactor during protein maturation.

Original languageEnglish (US)
Pages (from-to)227-239
Number of pages13
JournalArchives of Biochemistry and Biophysics
Issue number1
StatePublished - Jan 1 2005
Externally publishedYes


  • Atom transfer
  • Biogenesis
  • Cofactor
  • Copper
  • Free radical
  • Metalloradical
  • Oxidase
  • Oxidation-reduction
  • Self-processing
  • Tyrosyl-cysteine

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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