Iodotyrosine deiodinase, also known as iodotyrosine dehalogenase 1, is a type of deiodinaseenzyme that scavenges iodide by removing it from iodinated tyrosine residues in the thyroid gland.[5] These iodinated tyrosines are produced during thyroid hormone biosynthesis.[6] The iodide that is scavenged by iodotyrosine deiodinase is necessary to again synthesize the thyroid hormones.[7] After synthesis, the thyroid hormones circulate through the body to regulate metabolic rate, protein expression, and body temperature.[8] 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;[9] 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.[8] Although these two enzymes perform similar functions, they are structurally and mechanistically different. Iodothyronine deiodinase (not the enzyme that is the topic of this article) uses a selenocysteine active site for catalysis, is a member of the thioredoxin superfamily, and removes iodide only when the substrate is in a double-tyrosine form.[10] By contrast, iodotyrosine deiodinase (the topic enzyme) does not require selenocysteine or cysteine for catalysis,[11] is part of the NADH oxidase/flavin reductase superfamily,[12][13] and removes iodide when the substrate is a single amino acid.[14] Research on iodotyrosine deiodinase has historically been variable and slow due to its lack of stability and arduous purification.[15] Only recently has this enzyme been studied more deeply.[8]
