Reactome: A Curated Pathway Database

FMO3:FAD N-oxidises TMA to TMAO

Stable Identifier
R-HSA-139970
Type
Reaction
Species
Homo sapiens
Compartment
Synonyms
Trimethylamine N-oxidised to Trimethylamine-N-oxide
Locations in the PathwayBrowser
Summation

Trimethylamine (TMA) is present in the diet (in fish) but primarily formed in vivo from the breakdown of choline. It is N-oxidised by FMO3 in the liver, the major isoform active towards TMA, to form trimethylamine-N-oxide (TMAO). Trimethylaminuria (fish-odour syndrome) is a human genetic disorder characterised by an impaired ability to convert the malodourous TMA to the odourless N-oxide form TMAO (Higgins et al. 1972, Humbert et al. 1970, Treacy et al. 1998). L-carnitine is an abundant component of red meat and contains a trimethylamine structure similar to that of choline. Gut microbiota is able to produce TMAO from L-carnitine. If high levels of L-carnitine via high red meat intake or dietary supplements is achieved, Koeth et al. have shown the resultant TMAO produced in the gut can accelerate atherosclerosis in mice and increase the risk of cardiovascular disease (CVD) (Koeth et al. 2013).

Literature References
Participants
Participant Of
This entity is regulated by:
Title Physical Entity Activity
N,N-dimethylaniline monooxygenase activity of FMO3:FAD [endoplasmic reticulum membrane] FMO3:FAD [endoplasmic reticulum membrane] N,N-dimethylaniline monooxygenase activity (0004499)
Orthologous Events
Cross References
Rhea