IUBMB Enzyme Nomenclature


Accepted name: dibenzothiophene sulfone monooxygenase

Reaction: dibenzothiophene-5,5-dioxide + FMNH2 + NADH + O2 = 2′-hydroxybiphenyl-2-sulfinate + H2O + FMN + NAD+ + H+ (overall reaction)
(1a) FMNH2 + O2 = FMN-N5-peroxide
(1b) dibenzothiophene-5,5-dioxide + FMN-N5-peroxide = 2′-hydroxybiphenyl-2-sulfinate + FMN-N5-oxide
(1c) FMN-N5-oxide + NADH = FMN + H2O + NAD+ + H+ (spontaneous)

Glossary: dibenzothiophene-5,5-dioxide = dibenzothiophene sulfone

Other name(s): dszA (gene name)

Systematic name: dibenzothiophene-5,5-dioxide,FMNH2:oxygen oxidoreductase

Comments: This bacterial enzyme catalyses a step in the desulfurization pathway of dibenzothiophenes. The enzyme forms a two-component system with a dedicated NADH-dependent FMN reductase (EC encoded by the dszD gene, which also interacts with EC, dibenzothiophene monooxygenase. The flavin-N5-oxide that is formed by the enzyme reacts spontaneously with NADH to give oxidized flavin, releasing a water molecule.

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


1. Gray, K.A., Pogrebinsky, O.S., Mrachko, G.T., Xi, L., Monticello, D.J. and Squires, C.H. Molecular mechanisms of biocatalytic desulfurization of fossil fuels. Nat. Biotechnol. 14 (1996) 1705-1709. [PMID: 9634856]

2. Ohshiro, T., Kojima, T., Torii, K., Kawasoe, H. and Izumi, Y. Purification and characterization of dibenzothiophene (DBT) sulfone monooxygenase, an enzyme involved in DBT desulfurization, from Rhodococcus erythropolis D-1. J. Biosci. Bioeng. 88 (1999) 610-616. [PMID: 16232672]

3. Konishi, J., Ishii, Y., Onaka, T., Ohta, Y., Suzuki, M. and Maruhashi, K. Purification and characterization of dibenzothiophene sulfone monooxygenase and FMN-dependent NADH oxidoreductase from the thermophilic bacterium Paenibacillus sp. strain A11-2. J. Biosci. Bioeng. 90 (2000) 607-613. [PMID: 16232919]

4. Ohshiro, T., Ishii, Y., Matsubara, T., Ueda, K., Izumi, Y., Kino, K. and Kirimura, K. Dibenzothiophene desulfurizing enzymes from moderately thermophilic bacterium Bacillus subtilis WU-S2B: purification, characterization and overexpression. J. Biosci. Bioeng. 100 (2005) 266-273. [PMID: 16243275]

5. Adak, S. and Begley, T.P. Dibenzothiophene catabolism proceeds via a flavin-N5-oxide intermediate. J. Am. Chem. Soc. 138 (2016) 6424-6426. [PMID: 27120486]

6. Adak, S. and Begley, T.P. Flavin-N5-oxide: A new, catalytic motif in flavoenzymology. Arch. Biochem. Biophys. 632 (2017) 4-10. [PMID: 28784589]

7. Matthews, A., Saleem-Batcha, R., Sanders, J.N., Stull, F., Houk, K.N. and Teufel, R. Aminoperoxide adducts expand the catalytic repertoire of flavin monooxygenases. Nat. Chem. Biol. 16 (2020) 556-563. [PMID: 32066967]

[EC created 2016, modified 2019]

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