Trimethylamine N-oxide reductase
Trimethylamine N-oxide reductase (TOR or TMAO reductase, EC 1.7.2.3) is a microbial enzyme that can reduce trimethylamine N-oxide (TMAO) into trimethylamine (TMA), as part of the electron transport chain. The enzyme has been purified from E. coli and the photosynthetic bacteria Roseobacter denitrificans.[1] In general, it catalyzes the chemical reaction
- NADH + H+ + trimethylamine N-oxide NAD+ + trimethylamine + H2O
| trimethylamine-N-oxide reductase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 1.7.2.3 | ||||||||
| CAS number | 37256-34-1 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
The 3 substrates of this enzyme are NADH, H+, and trimethylamine N-oxide, whereas its 3 products are NAD+, trimethylamine, and H2O.
However, both the R. denitrificans and E. coli enzymes can accept electrons from cytochromes.:[2]
- trimethylamine + 2 (ferricytochrome c)-subunit + H2O → trimethylamine N-oxide + 2 (ferrocytochrome c)-subunit + 2 H+
Trimethylamine oxide is found at high concentrations in the tissues of fish, and the bacterial reduction of this compound to foul-smelling trimethylamine is a major process in the spoilage of fish.[3]
References
- Arata H, Shimizu M, Takamiya K (1992). "Purification and properties of trimethylamine N-oxide reductase from aerobic photosynthetic bacterium Roseobacter denitrificans". J. Biochem. 112 (4): 470–5. doi:10.1093/oxfordjournals.jbchem.a123923. PMID 1337081.
- Gon S, Giudici-Orticoni MT, Méjean V, Iobbi-Nivol C (2001). "Electron transfer and binding of the c-type cytochrome TorC to the trimethylamine N-oxide reductase in Escherichia coli". J. Biol. Chem. 276 (15): 11545–51. doi:10.1074/jbc.M008875200. PMID 11056172.
- Barrett EL, Kwan HS (1985). "Bacterial reduction of trimethylamine oxide". Annu. Rev. Microbiol. 39: 131–49. doi:10.1146/annurev.mi.39.100185.001023. PMID 3904597.
Further reading
- Unemoto T, Hayashi M, Miyaki K, Hayashi M (1965). "Intracellular localization and properties of trimethylamine-N-oxide reductase in Vibrio parahaemolyticus". Biochim. Biophys. Acta. 110 (2): 319–28. doi:10.1016/s0926-6593(65)80039-x. PMID 4286289.