Why is FMO3 such a suspect for fecal body odor ?

My own suspicion is that enzyme FMO3 is most likely to blame for 'fecal body odor' (although recently I have started more considering hypermethionemia as a potential suspect enzyme too). Still, at the moment I suspect 'fecal body odor' may be 'FMO3 body odor'.

Here's why :

Many enzymes deal with 1 or only a few 'substrates' (i.e. metabolites), that tend to have the same construction and if they have an odor it is likelty to be a particular odor (such as sweaty feet odor in isovaleric acidemia). FMO3 deals with 1,000s of various substrates that have a sulfur, nitrogen, or phosphorous molecule (in particular, sulfides and amines are known to be smelly)

FMO3 is a drug metabolizing enzyme, a xenobiotic metabolizing enzyme, a endogenous metabolizing enzyme,  which deals with 1,000's of substrates

Most other enzymes seem to be mostly endogenous metabolizing enzymes that have very few substrates

At the moment it is known that trimethylamine is a FMO3 substrate and the only one known to have no alternative route for oxidation. Although there are 1,000s of other FMO3 substrates, currently experts believe only TMA will cause a smell. They must think that either the other substrates with no alternative pathway are unknown, or that they can go alternative pathways for oxidizing. My opinion is that it is very possible the other pathways become 'backed up' with these constant load of FMO3 substrates, most coming from the gut.

So, for now, I still think 'fecal body odor' is 'FMO3 body odor', but this is before any proof one way or the other is demonstrated. I am open-minded for it being another enzyme (or even a few enzymes)

By sysbodyodor

fecal body odor, fmo3

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