title: Biochemistry of iodothyronine deiodination.
abstract: Extrathyroidal deiodination of the thyroidal main secretory product L-T4, which may have prohormone functions, reveals hormonally active and potentially regulatory potent triiodothyronines. The regulation of these enzyme reactions is still unknown but three deiodinase isoenzymes can be classified based on their physicochemical, kinetic, pharmacological and physiological properties. The purification to homogeneity and cloning of the substrate binding 27kDa subunit of 5'-deiodinase type I is currently performed and these experiments suggest a close similarity of this subunit in 5'D I and II, no evidence is found yet supporting a structural relationship to other ITH binding, transport, metabolizing or receptor proteins, in spite of a high similarity of the hormone binding sites of 5'D I and hTBPA.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D006801:Humans; D007453:Iodide Peroxidase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D013970:Thyronines / Q000378:metabolism*; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D013970:Thyronines; D014284:Triiodothyronine; D007453:Iodide Peroxidase; D013974:Thyroxine