Flavin-containing monooxygenase 3 (FMO3), also known as
dimethylaniline monooxygenase -oxide-forming3 and
trimethylamine monooxygenase, is a
flavoprotein enzyme () that in humans is encoded by the ''FMO3''
gene.
This enzyme
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
the following
chemical reaction, among others:
:trimethylamine + NADPH + H
+ + O
2 trimethylamine ''N''-oxide + NADP
+ + H
2O
FMO3 is the main
flavin-containing monooxygenase isoenzyme that is expressed in the liver of adult humans.
The human FMO3 enzyme catalyzes several types of reactions, including: the of primary, secondary, and tertiary
amines;
the of
nucleophilic sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
-containing compounds;
and the of the anti-cancer agent dimethylxanthenone acetic acid (
DMXAA
Vadimezan (also known as or ASA404 and dimethylxanthone acetic acid or DMXAA) is a tumor-vascular disrupting agent (tumor-VDA) that attacks the blood supply of a cancerous tumor to cause tumor regression.
Clinical trials Non-small cell lung canc ...
).
FMO3 is the primary enzyme in humans which catalyzes the
''N''-oxidation of trimethylamine into trimethylamine ''N''-oxide;
also does this, but to a much lesser extent than FMO3.
Genetic deficiencies of the FMO3 enzyme cause
primary trimethylaminuria, also known as "fish odor syndrome".
FMO3 is also involved in the metabolism of many
xenobiotics (i.e., exogenous compounds which are not normally present in the body),
such as the
oxidative deamination Oxidative deamination is a form of deamination that generates α-keto acids and other oxidized products from amine-containing compounds, and occurs primarily in the liver. Oxidative deamination is stereospecific, meaning it contains different stere ...
of
amphetamine
Amphetamine (contracted from alpha- methylphenethylamine) is a strong central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. It is also commonly used ...
.
Table 5: N-containing drugs and xenobiotics oxygenated by FMO
br
Table 6: S-containing drugs and xenobiotics oxygenated by FMO
br
Table 7: FMO activities not involving S- or N-oxygenation
/ref>
Ligands
Cancer
FMO3 gene has been observed progressively downregulated in Human papillomavirus-positive neoplastic keratinocytes derived from uterine cervical preneoplastic lesions at different levels of malignancy.
See also
* Flavin-containing monooxygenase
* Trimethylaminuria
References
Further reading
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External links
*
Primary Trimethylaminuria (FMO3 Deficiency)
– NCBI bookshelf GeneReviews entry
{{Nitrogenous transferases
Amphetamine
Flavoprotein enzymes