Physical Sciences and Mathematics Commons^™

Shewanella Oneidensis Cytochrome C Nitrite Reductase (Ccnir) Does Not Disproportionate Hydroxylamine To Ammonia And Nitrite, Despite A Strongly Favorable Driving Force, Matthew Youngblut, Daniel J. Pauly, Natalia Stein, Daniel Walters, John A. Conrad, Graham R. Moran, Brian Bennett, A. Andrew Pacheco

Physics Faculty Research and Publications

Cytochrome c nitrite reductase (ccNiR) from Shewanella oneidensis, which catalyzes the six-electron reduction of nitrite to ammonia in vivo, was shown to oxidize hydroxylamine in the presence of large quantities of this substrate, yielding nitrite as the sole free nitrogenous product. UV–visible stopped-flow and rapid-freeze-quench electron paramagnetic resonance data, along with product analysis, showed that the equilibrium between hydroxylamine and nitrite is fairly rapidly established in the presence of high initial concentrations of hydroxylamine, despite said equilibrium lying far to the left. By contrast, reduction of hydroxylamine to ammonia did not occur, even though disproportionation of hydroxylamine to …