Fig. 2.
NO production by mHAO from Methylacidiphilum fumariolicum SolV. (A) Sample trace of NO production by mHAO from 5 µM NH2OH measured with membrane inlet mass spectrometry (MIMS). Hydroxylamine oxidation assays by mHAO with varying concentrations of hydroxylamine (2 to 5 µM), resulting in a recovery rate of 94 ± 4% (n = 6) of NO compared to the added amount of hydroxylamine. (B) Sample trace of cytochrome c reduction by mHAO with hydroxylamine. Addition of 1 µM hydroxylamine resulted in the reduction of 3 ± 0.06 µM (n = 3) cytochrome c, indicating the three-electron oxidation of hydroxylamine to NO by mHAO.