page_title: Iodotyrosine deiodinase
section_title: Mechanism
hierarchical_section_title: Iodotyrosine deiodinase / Mechanism
caption_attribution_description: English: This is the corrected reaction scheme for the enzyme iodotyrosine deiodinase. There was a typo in the other figure I posted. I had Ph as a member on the substrate ring instead of OH, as it should be.
context_page_description: Iodotyrosine deiodinase, also known as iodotyrosine dehalogenase 1, is a type of deiodinase enzyme that scavenges iodide by removing it from iodinated tyrosine residues in the thyroid gland. These iodinated tyrosines are produced during thyroid hormone biosynthesis. The iodide that is scavenged by iodotyrosine deiodinase is necessary to again synthesize the thyroid hormones. After synthesis, the thyroid hormones circulate through the body to regulate metabolic rate, protein expression, and body temperature. Iodotyrosine deiodinase is thus necessary to keep levels of both iodide and thyroid hormones in balance.
  Dehalogenation in aerobic organisms is usually done through oxidation and hydrolysis; however, iodotyrosine deiodinase uses reductive dehalogenation. Iodotyrosine deiodinase and iodothyronine deiodinase have been determined as the only two known enzymes to catalyze reductive dehalogenation in mammals. Although these two enzymes perform similar functions, they are structurally and mechanistically different.
context_section_description: Iodotyrosine deiodinase catalyzes mono- and diiodotyrosine deiodination. The reaction is NADPH-dependent.  Flavin mononucleotide (FMN) is a cofactor. Although flavin is commonly utilized in various catalytic reactions, its use in this reductive dehalogenation is unique and not yet fully understood. It is also still unclear if the enzyme mechanism utilizes a two electron transfer reaction or a series of one electron transfers. Although further research must be done to determine details of this mechanism, recent evidence seems to suggest that iodotyrosine deiodinase acts through one electron transfer reactions.
caption: Iodotyrosine deiodinase reaction scheme.[7]
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