Deiodinase (EC 1.97.1.10) is an enzyme important in the action of thyroid hormones. The Entrez Global Query Cross-Database Search System is a powerful Federated search engine or Web portal that allows users to search many discrete Health sciences The Human Genome Organisation (HUGO is an organization involved in the Human Genome Project, a project about mapping the human genome The Mendelian Inheritance in Man project is a Database that catalogues all the known Diseases with a genetic component, and—when possible—links them The National Center for Biotechnology Information ( NCBI) is part of the United States National Library of Medicine (NLM a branch of the National Institutes Swiss-Prot is a manually curated Biological database of Protein sequences In the fields of Genetics and Evolutionary computation, a locus (plural loci) is a fixed position on a Chromosome such as the position of a Chromosome 14 is one of the 23 pairs of Chromosomes in Humans People normally have two copies of this chromosome This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins The thyroid hormones, Thyroxine ( T4) and Triiodothyronine ( T3) are Tyrosine -based Hormones produced Deiodinases are unusual in that the enzyme contains selenium, in the form of an otherwise rare amino acid selenocysteine. Selenium (səˈliniəm is a Chemical element with the Atomic number 34 represented by the chemical symbol Se, an atomic mass of 78 In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Selenocysteine is an Amino acid that is present in several Enzymes (for example Glutathione peroxidases tetraiodothyronine 5' deiodinases ^[1][2][3]

Activation and inactivation

In the tissues, deiodinases can either activate or inactivate thyroid hormones:

• Activation occurs by conversion of the prohormone thyroxine (T₄) to the active hormone triiodothyronine (T₃) through the removal of an iodine atom on the outer ring. A prohormone is a substance that is a precursor to a Hormone, usually having minimal hormonal effect by itself Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the Triiodothyronine, C15[[hydrogen H12]] I3[[nitrogen N]] O4, also known as T3, is a Thyroid Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic
• Inactivation of thyroid hormones occurs by removal of an iodine atom on the inner ring, which converts thyroxine to the inactive reverse triiodothyronine (rT₃), or which converts the active triiodothyronine to the inactive diiodothyronine (T₂). Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Triiodothyronine, C15[[hydrogen H12]] I3[[nitrogen N]] O4, also known as T3, is a Thyroid 33'-Diiodothyronine is a metabolite of Thyroid hormone. It is formed from the breakdown of tri-iodothyronine (T3 The major part of thyroxine deiodination occurs within the cells. Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the

Types

In most vertebrates, there are three types of enzymes that can deiodinate thyroid hormones:

Reactions

Reactions catalyzed by specific deiodinase isoforms

References

External links

• MeSH Deiodinase