Purification of hydroxylamine oxidase from Thiosphaera pantotropha. Identification of electron acceptors that couple heterotrophic nitrification to aerobic denitrification

Josa Marie Wehrfritz, Ann Reilly, Stephen Spiro, David J. Richardson

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108 Citations (Scopus)


Thiosphaera pantotropha, a Gram-negative heterotrophic nitrifying bacterium, expresses a soluble 20 kDa monomeric periplasmic hydroxylamine oxidase that differs markedly from the hydroxylamine oxidase found in autotrophic bacteria. This enzyme can use the periplasmic redox proteins, cytochrome C551 and pseudoazurin as electron acceptors, both of which can also donate electrons to denitrification enzymes. A model of electron transfer is proposed, that suggests a coupling of nitrification to denitrification and provides a mechanism by which nitrification can play a role in dissipating reductant.

Original languageEnglish
Pages (from-to)246-250
Number of pages5
JournalFEBS Letters
Issue number2
Publication statusPublished - 6 Dec 1993


  • Denitrification
  • Hydroxylamine oxidase
  • Nitrification
  • Thiosphaera pantotropha

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