Identification of an N-hydroxyguanidine reducing activity of xanthine oxidase

Maija Dambrova, Staffan Uhlén, Christopher J. Welch, Jarl E.S. Wikberg

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A guanoxabenz [1-(2,6-dichlorobenzylideneamino)-3-hydroxyguanidine; an N-hydroxyguanidine] reducing enzymatic activity of rat spleen cytosol was investigated by means of protein purification and N-terminal amino acid sequencing, the reducing activity was shown to reside in xanthine oxidase. The action of the enzyme on guanoxabenz resulted in the formation of guanabenz [1-(2,6-dichlorobenzylideneamino) -3-guanidine]; the product formation could be monitored by HPLC and its identity was confirmed by NMR analysis. The reduction of guanoxabenz required xanthine or NADH as reducing substrates, while the process could be blocked by allopurinol, a selective inhibitor of xanthine oxidase. By using bovine milk xanthine oxidase, the guanoxabenz reducing activity of the enzyme was also verified. We conclude that guanoxabenz is a novel electron acceptor structure for xanthine oxidase.

Original languageEnglish
Pages (from-to)178-184
Number of pages7
JournalEuropean Journal of Biochemistry
Issue number1
Publication statusPublished - 1 Oct 1998
Externally publishedYes


  • Guanoxabenz
  • N-hydroxyguanidine
  • Reduction
  • Xanthine oxidase

Field of Science*

  • 1.4 Chemical sciences
  • 1.6 Biological sciences
  • 3.1 Basic medicine

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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