Deiodinase
Deiodases (deiodinase is the English term) are selenoenzymes that activate or inactivate thyroid hormones such as iodothyronine , thyronamine and iodothyroacetate through stereospecific deiodination.
A distinction is made between three deiodases: Type I deiodase (gene symbol: DIO1), Type II deiodase (DIO2) and Type III deiodase (DIO3). All three are able to remove iodine atoms from thyroid hormones , thyronamines and iodothyroacetates . The iodine atoms on the inner ring of iodothyronines are in the 3- and 5-positions, while the iodine atoms on the outer ring are referred to as the 3'- and 5'-iodine atoms. The removal of iodine atoms from the inner ring deactivates thyroid hormones.
DIO1 can catalyze both 5'-deiodination and 5-deiodination. DIO2 is a pure 5'-deiodase and can thus activate thyroxine to triiodothyronine, the active thyroid hormone. DIO3 is a 5-deiodase that inactivates thyroxine and triiodothyronine and thus terminates the thyroid hormone action.
Enzymes that can remove halogen atoms from aromatic rings
| family | Cofactor | Genes |
|---|---|---|
| Iodothyronine deiodinases | Selenocysteine | DIO1 , DIO2 , DIO3 |
| Iodotyrosine dehalogenase | Flavin | IYD |
literature
- SR Thomas et al .: Crystal structure of iodotyrosine deiodinase, a novel flavoprotein responsible for iodide salvage in thyroid glands. In: J. Biol. Chem. 284 (29), Jul 17, 2009, pp. 19659-19667. doi: 10.1074 / jbc.M109.013458 . PMC 2740591 (free full text). PMID 19436071 .
- U. Schweizer, C. Schlicker, D. Braun, J. Köhrle, C. Steegborn: Crystal structure of mammalian selenocysteine-dependent iodothyronine deiodinase suggests a peroxiredoxin-like catalytic mechanism. In: Proc Natl Acad Sci USA. 111 (29), Jul 2014, pp. 10526-10531. doi: 10.1073 / pnas.1323873111 . PMID 25002520 .