Biochemical characterization of the HpxO enzyme from Klebsiella pneumoniae, a novel FAD-dependent urate oxidase. Academic Article uri icon


  • The HpxO enzyme from Klebsiella pneumoniae was recently proposed, on the basis of genetic studies, to catalyze the hydroxylation of uric acid to 5-hydroxyisourate as part of the purine catabolic pathway. Its primary sequence suggests that the HpxO catalytic activity depends on a flavin cofactor (FAD), contrasting with all previously studied urate oxidase enzymes, which have no cofactor requirement. Here we demonstrate biochemically that HpxO is an FAD-dependent urate oxidase. Our data are consistent with the proposal that HpxO-bound flavin hydroperoxide is the hydroxylating species. These results confirm the existence of a novel mechanistic paradigm in purine catabolism.

published proceedings

  • Biochemistry

altmetric score

  • 3

author list (cited authors)

  • O'Leary, S. E., Hicks, K. A., Ealick, S. E., & Begley, T. P.

citation count

  • 10

complete list of authors

  • O'Leary, Se├ín E||Hicks, Katherine A||Ealick, Steven E||Begley, Tadhg P

publication date

  • April 2009