Nitration chemistry represents an excellent tool for accessing complex pharmaceutical molecules, and the existing nitration chemistry almost exclusively relies on chemical catalysts [1]. Compared to chemical catalysts, enzyme biocatalysts have several advantages such as high selectivity and mild reaction conditions. However, enzymes have never been explored to synthesize nitro compounds. In this presentation, I will discuss our recent work on the discovery, characterization, and engineering of novel N-oxygenases that catalyze oxidation of primary and secondary amines. The first enzyme, PrnD, is a Rieske mononuclear non-heme iron enzyme involved in the biosynthesis of pyrrolnitrin [2-3]. The second enzyme, AurF, is a diiron enzyme that catalyzes the formation of novel polyketide synthase starter unit p-nitrobenzoate from p-aminobenzoate [4]. The third enzyme, FrbG, is a FAD-dependent monooxygenase involved in the biosynthesis of FR900098 that catalyzes an unprecedented oxidation of a secondary amine.