Valanimycin, an antibiotic with antitumor activity, is produced by Streptomyces viridifaciens MG456-hF10. This molecule contains an azoxy group and is being studied to learn more about the synthesis of naturally occurring azoxy compounds ([http://www.ncbi.nlm.nih.gov/pubmed/12688722|Tao et al., 2003]. Valanimycin is synthesized by condensation of L-serine with isobutylhydroxylamine; the latter compound is produced from L-valine via isobutylamine. A key step in the synthesis pathway, the oxidation of isobutylamine to isobutylhydroxylamine, is catalysed by a two-component flavin monooxygenase. The two components are isobutylamine N-hydroxylase and NAD(P)H:FAD oxidoreductase. The second component is required to provide reduced flavin cofactor since isobutylamine N-hydroxylase is unable to reduce FAD or FMN on its own. Purification of isobutylamine N-hydroxylase from Streptomyces viridifaciens has been reported ([http://www.ncbi.nlm.nih.gov/pubmed/9056232|Parry et al., 1997]). The exact mechanism of N-N bond formation is not very clear. However, [http://www.ncbi.nlm.nih.gov/pubmed/12688722|Tao et al. (2003)] have proposed 2 possible mechanisms for the incorporation of L-serine.