Thyroid hormone synthesis and metabolism enzymes

Thyroid hormone synthesis and metabolism enzymes are a collective group of proteins responsible for the production, activation, and degradation of thyroid hormones, which are vital for regulating metabolism, growth, and development [1.2.3, 1.3.3]. The primary enzyme in the biosynthetic pathway is thyroid peroxidase (TPO), a membrane-bound heme protein that catalyzes the oxidation of iodide and its attachment to thyroglobulin, as well as the coupling of iodotyrosine residues to form thyroxine (T4) and triiodothyronine (T3) [1.2.4, 1.4.2]. Peripheral metabolism is governed by iodothyronine deiodinases (DIO1, DIO2, and DIO3), which are selenoproteins that regulate the local and systemic availability of active T3 by removing specific iodine atoms from the hormone rings [1.2.1, 1.2.5]. Other enzymes in this group, such as dual oxidase 2 (DUOX2) and iodotyrosine deiodinase (IYD), also play critical roles in providing substrates and recycling iodine for hormone production [1.3.3, 1.4.1].\n\nThese enzymes are key therapeutic targets in the management of thyroid disorders; for instance, thionamides like methimazole and propylthiouracil are used to treat hyperthyroidism by inhibiting TPO-mediated hormone synthesis [1.4.1, 1.4.5]. Additionally, propylthiouracil and certain radiographic contrast agents inhibit DIO1 to reduce the peripheral conversion of T4 to T3 during thyrotoxic crises [1.4.4]. Monitoring these pathways involves biomarkers such as TSH, free T4, and TPO antibodies, while therapeutic use of inhibitors requires vigilance for serious side effects like agranulocytosis and hepatotoxicity [1.1.2, 1.3.1, 1.4.2]. Overall, this enzymatic network ensures precise control over thyroid hormone levels to meet the physiological demands of various tissues [1.2.5, 1.3.2].

Other names

Thyroid hormone biosynthetic enzymesThyroid hormone metabolic enzymesThyroid peroxidase (TPO)Iodothyronine deiodinases (DIO1, DIO2, DIO3)Dual oxidase 2 (DUOX2)Iodotyrosine deiodinase (IYD)Thionamide targets

Inhibition of thyroid peroxidase (TPO) to block the iodination of thyroglobulin and the coupling of iodotyrosines; Inhibition of type 1 deiodinase (DIO1) to prevent the peripheral conversion of thyroxine (T4) to the more active triiodothyronine (T3) [1.2.2, 1.4.2, 1.4.4].