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      Characterization of an O2 Adduct of an Active Cobalt-Substituted Extradiol-Cleaving Catechol Dioxygenase

      1 , 1 , 1
      Journal of the American Chemical Society
      American Chemical Society (ACS)

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          Abstract

          The first example of an O(2) adduct of an active Co-substituted oxygenase has been observed in the extradiol ring cleavage of the electron-poor substrate 4-nitrocatechol (4NC) by Co(II)-homoprotocatechuate 2,3-dioxygenase (Co-HPCD). Upon O(2) binding to the high-spin Co(II) (S = (3)/(2)) enzyme-substrate complex, an S = (1)/(2) EPR signal exhibiting (59)Co hyperfine splitting (A = 24 G) typical of a low-spin Co(III)-superoxide complex was observed. Both the formation and decay of the new intermediate are very slow in comparison to the analogous steps for turnover of 4NC by native high-spin Fe(II)-HPCD, which is likely to remain high-spin upon O(2) binding. A similar but effectively stable S = (1)/(2) intermediate was formed by the inactive [H200N-Co-HPCD(4NC)] variant. The observations presented shed light on the key roles played by the substrate, the second-sphere His200 residue, and the spin state of the metal center in facilitating O(2) binding and activation.

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          Author and article information

          Journal
          Journal of the American Chemical Society
          J. Am. Chem. Soc.
          American Chemical Society (ACS)
          0002-7863
          1520-5126
          December 21 2011
          January 18 2012
          December 29 2011
          January 18 2012
          : 134
          : 2
          : 796-799
          Affiliations
          [1 ]Department of Chemistry and ‡Department of Biochemistry, Molecular Biology, and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
          Article
          10.1021/ja2095365
          3262093
          22175783
          e024e705-2973-4dba-b3cd-982a057d72fd
          © 2012
          History

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