IUBMB Enzyme Nomenclature


Accepted name: L-ornithine N5-monooxygenase [NAD(P)H]

Reaction: L-ornithine + NAD(P)H + H+ + O2 = N5-hydroxy-L-ornithine + NAD(P)+ + H2O

Other name(s): SidA (ambiguous)

Systematic name: L-ornithine,NAD(P)H:oxygen oxidoreductase (N5-hydroxylating)

Comments: A flavoprotein (FAD). The enzyme from the pathogenic fungus Aspergillus fumigatus catalyses a step in the biosynthesis of the siderophores triacetylfusarinine and desferriferricrocin, while the enzyme from the bacterium Kutzneria sp. 744 is involved in the biosynthesis of piperazate, a building block of the kutzneride family of antifungal antibiotics. Activity of the fungal enzyme is higher with NADPH, due to the fact that following the reduction of the flavin, NADP+ (but not NAD+) stabilizes the C4a-hydroperoxyflavin intermediate that oxidizes the substrate [3]. cf. EC, L-ornithine N5-monooxygenase (NADPH).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Chocklett, S.W. and Sobrado, P. Aspergillus fumigatus SidA is a highly specific ornithine hydroxylase with bound flavin cofactor. Biochemistry 49 (2010) 6777-6783. [PMID: 20614882]

2. Franceschini, S., Fedkenheuer, M., Vogelaar, N.J., Robinson, H.H., Sobrado, P. and Mattevi, A. Structural insight into the mechanism of oxygen activation and substrate selectivity of flavin-dependent N-hydroxylating monooxygenases. Biochemistry 51 (2012) 7043-7045. [PMID: 22928747]

3. Romero, E., Fedkenheuer, M., Chocklett, S.W., Qi, J., Oppenheimer, M. and Sobrado, P. Dual role of NADP(H) in the reaction of a flavin dependent N-hydroxylating monooxygenase. Biochim. Biophys. Acta 1824 (2012) 850-857. [PMID: 22465572]

4. Neumann, C.S., Jiang, W., Heemstra, J.R., Jr., Gontang, E.A., Kolter, R. and Walsh, C.T. Biosynthesis of piperazic acid via N5-hydroxy-ornithine in Kutzneria spp. 744. Chembiochem 13 (2012) 972-976. [PMID: 22522643]

[EC created 2014]

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