Cr(II) reactivity of taurine/alpha-ketoglutarate dioxygenase

Inorg Chem. 2007 Nov 26;46(24):10087-92. doi: 10.1021/ic700383q. Epub 2007 Nov 1.


The interaction of CrII with taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with alphaKG to the FeII/alphaKG binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen-sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This preformed side chain is generated by intracellular self-hydroxylation of Tyr-73 to form DOPA, which is subsequently oxidized to the quinone. No chromophore is generated when using NaBH4-treated sample, protein isolated from anaerobically grown cells, inactive TauD variants that are incapable of self-hydroxylation, or the Y73F active mutant of TauD. A CrIII-DOPA semiquinone also was observed in the herbicide hydroxylase SdpA.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Binding Sites
  • Catalysis
  • Chromium / chemistry*
  • Chromium / metabolism
  • Dihydroxyphenylalanine / chemistry
  • Dihydroxyphenylalanine / metabolism
  • Ferrous Compounds / chemistry
  • Ferrous Compounds / metabolism
  • Mixed Function Oxygenases / genetics
  • Mixed Function Oxygenases / metabolism*
  • Molecular Structure
  • Tyrosine / chemistry
  • Tyrosine / metabolism


  • Ferrous Compounds
  • Chromium
  • Tyrosine
  • Dihydroxyphenylalanine
  • Mixed Function Oxygenases
  • taurine-alpha-ketoglutarate dioxygenase