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| Name = thyroxine 5'-deiodinase | EC_number = | IUBMB_EC_number = 1/97/1/10 | CAS_number= 70712-46-8 | GO_code = 0004800 | image = | width = | caption = }} Deiodinase (or iodide peroxidase or "Monodeiodinase") is a peroxidase enzyme that is involved in the activation or deactivation of thyroid hormones.


Types of deiodinases include:

family prosthetic group genes
Iodothyronine deiodinase selenium DIO1, DIO2, DIO3
Iodotyrosine deiodinase flavin IYD

In general, T4 (thyroxine) is converted into T3 (triiodothyronine) or rT3 (reverse triiodothyronine) by the iodothyronine deiodinase enzyme in target cells.

Starvation response[edit]

In starvation, deiodinase (to be specific, Deiodinase I) is inhibited thus lowering basal metabolic rate. However, in the brain, heart, skeletal muscle and thyroid, this is not so, as these organs must maintain homeostasis (skeletal muscle through shivering can increase temperature). This is achieved by the latter organs expressing deiodinase II rather than Deiodinase I as in most peripheral tissues.[citation needed]


selenium which is the prosthetic group of iodotyrosine deiodinase ,as selenocysteine, plays a crucial role in determinig the free circulating levels of T3. Selenium defeciency can have implications in fall of T3 levels.

External links[edit]