Official Full Name
Tyramine Oxidase
Background
Amine oxidases (AO) are enzymes that catalyze the oxidation of a wide range of biogenic amines including many neurotransmitters, histamine and xenobiotic amines. There are two classes of amine oxidases: flavin-containing (EC 1.4.3.4) and copper-containing (EC 1.4.3.6). Copper-containing AO act as a disulphide-linked homodimer. They catalyse the oxidation of primary amines to aldehydes, with the subsequent release of ammonia and hydrogen peroxide, which requires one copper ion per subunit and topaquinone as cofactor: RCH2NH2 + H2O + O2 ↔ RCHO + NH3 + H2O2. The 3 substrates of this enzyme are primary amines (RCH2NH2), H2O, and O2, whereas its 3 products are RCHO, NH3, and H2O2.
Synonyms
Tyramine Oxidase; TOD; EC 1.4.3.6
Introductions
Tyramine oxidase is a copper enzyme present in the cytoplasm of animal cells that catalyzes the oxidation of phenolic amine substrates.
Structure
Tyramine oxidase belongs to the copper enzyme superfamily with a molecular weight of about 130 kDa and consists of two homologous subunits. Tyramine oxidase binds to two copper ions through four sites, three of which are known as type 1 copper and are involved in the catalysis of substrate oxidation. The other site, known as type 2 copper, acts as an electron transfer. In addition, tyramine oxidase has multiple cysteine residues that form disulfide bonds and maintain the stability of the enzyme.
Mechanism
Tyramine oxidase acts mainly on phenolic amines in the body, such as tyramine and epinephrine. It is able to oxidize these compounds to produce the corresponding aldehydes and hydrogen peroxide. Phenolic amines play an important neurotransmitter and hormonal role in the body, and the presence of tyramine oxidase allows them to be efficiently metabolized and cleared, thus maintaining homeostasis in the body. In addition, tyramine oxidase is involved in biodegradation and drug metabolism. It metabolizes some drugs such as isoprenaline and phenylpropanol, which are also associated with neurotransmitter and hormonal actions in the body.
Applications
Tyramine oxidase can be used as a biomarker for detecting myocardial injury because phenolic amines are released when myocardial cells are damaged. The extent and prognosis of myocardial injury can be determined by measuring the relationship between phenolamine compounds and tyramine oxidase activity in serum or urine. In addition, tyramine oxidase is also widely used in the food and pharmaceutical processing industries. Many foods such as dairy products and wine contain tyramine, which can lead to tyramine poisoning if not metabolized in time. This can be effectively avoided by using tyramine oxidase for tyramine degradation. Also, tyramine oxidase can be used for the metabolism and synthesis of pharmaceuticals, which has important application prospects in pharmaceutical research and development.
Physiological significance
Tyramine oxidase plays a crucial role in maintaining homeostasis in the body. It has been shown that deficiency or abnormal function of tyramine oxidase can lead to the development of a range of diseases, such as hypertension, asthma, and depression. The development of these diseases is associated with the accumulation of phenolic amines in the body. In addition, the activity of tyramine oxidase is affected by genetic polymorphisms. Mutations in the tyramine oxidase gene vary in different populations, which may lead to different genetic disorders or individual differences. Therefore, the study of genetic polymorphisms of tyramine oxidase is important to elucidate the mechanisms of related diseases and individualized treatment.
Conclusions
In conclusion, tyramine oxidase is an important copper enzyme involved in the metabolism and clearance of phenolamine compounds in vivo, and has an important role in maintaining homeostasis in vivo. Its structure, function, physiological significance and its medical and industrial applications are worthy of in-depth study. A deeper understanding of tyramine oxidase may be able to elucidate the mechanisms of some related diseases and provide new ideas for the development of novel drugs and food processing technologies.
