Diamine oxidase (DAO), also known "amine oxidase, copper-containing, 1" (AOC1), formerly called histaminase, is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

() involved in the metabolism, oxidation, and inactivation of

histamine Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discover ...

and other

polyamines A polyamine is an organic compound having more than two amino groups. Alkyl polyamines occur naturally, but some are synthetic. Alkylpolyamines are colorless, hygroscopic, and water soluble. Near neutral pH, they exist as the ammonium derivatives. ...

such as

putrescine Putrescine is an organic compound with the formula (CH2)4(NH2)2. It is a colorless solid that melts near room temperature. It is classified as a diamine. Together with cadaverine, it is largely responsible for the foul odor of putrefying flesh ...

spermidine Spermidine is a polyamine compound () found in ribosomes and living tissues and having various metabolic functions within organisms. It was originally isolated from semen. Function Spermidine is an aliphatic polyamine. Spermidine synthase (SPDS ...

in animals. It belongs to the

amine oxidase (copper-containing) Amine oxidase (copper-containing) (AOC) ( and ; formerly ) is a family of amine oxidase enzymes which includes both primary-amine oxidase and diamine oxidase; these enzymes catalyze the oxidation of a wide range of biogenic amines including ...

(AOC) family of

amine oxidase An amine oxidase is an enzyme that catalyzes the oxidative cleavage of alkylamines into aldehydes and ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictoge ...

enzymes. In humans, DAO it is encoded by ''AOC1'' gene. The highest levels of DAO expression are observed in the digestive tract and the

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...

. In humans, a certain subtype of cells of the placenta, namely the extravillous

trophoblasts The trophoblast (from Greek : to feed; and : germinator) is the outer layer of cells of the blastocyst. Trophoblasts are present four days after fertilization in humans. They provide nutrients to the embryo and develop into a large part of the pl ...

, express the enzyme and secrete it into the blood stream of a pregnant woman. Lowered diamine oxidase values in maternal blood in early pregnancy might be an indication for trophoblast-related pregnancy disorders like early-onset

preeclampsia Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease ...

. Normally the enzyme is not or only very scarcely present in the blood circulation of humans, but it increases vastly in pregnant women suggesting a protective mechanism against adverse histamine. It is also secreted by

eosinophils Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...

. In case of a shortage of diamine oxidase in the human body, it may appear as an

allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...

or histamine intolerance.

Supplementation

For people with a histamine intolerance, the benefits of supplementation are inconclusive due to limited research.

References

External links

* EC 1.4.3 Histamine Copper enzymes {{oxidoreductase-stub