One of the hallmark reactions catalyzed by flavin-dependent enzymes is the incorporation of an oxygen atom derived from dioxygen into organic substrates. For many decades, these flavin monooxygenases were assumed to use exclusively the flavin-C4a-(hydro)peroxide as their oxygen-transferring intermediate. We demonstrate that flavoenzymes may instead employ a flavin-N5-peroxide as a soft α-nucleophile for catalysis, which enables chemistry not accessible to canonical monooxygenases. This includes, for example, the redox-neutral cleavage of carbon-hetero bonds or the dehalogenation of inert environmental pollutants via atypical oxygenations. We furthermore identify a shared structural motif for dioxygen activation and N5-functionalization, suggesting a conserved pathway that may be operative in numerous characterized and uncharacterized flavoenzymes from diverse organisms. Our findings show that overlooked flavin-N5-oxygen adducts are more widespread and may facilitate versatile chemistry, thus upending the notion that flavin monooxygenases exclusively function as nature’s equivalents to organic peroxides in synthetic chemistry.
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This work was supported by the Deutsche Forschungsgemeinschaft (DFG) by grant nos. TE 931/2–1 (awarded to R.T.) and 235777276/GRK1976 (R.T.) as well as the National Institute of General Medical Sciences and of the National Institutes of Health under Award Number F32GM122218 (J.N.S.). Computational resources were provided by the UCLA Institute for Digital Research and Education. We thank M. Boll, B. Palfey, C. Fanhi, B. Kammerer and S. Lagies for technical support.
The authors declare no competing interests.
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Matthews, A., Saleem-Batcha, R., Sanders, J.N. et al. Aminoperoxide adducts expand the catalytic repertoire of flavin monooxygenases. Nat Chem Biol 16, 556–563 (2020). https://doi.org/10.1038/s41589-020-0476-2
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