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CAS number 70-40-6
PubChem 65559
ChemSpider 59002 YesY
MeSH 3,3'-diiodothyronine
Jmol-3D images Image 1
Image 2
Molecular formula C15H13I2NO4
Molar mass 525.077 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

3,3'-Diiodothyronine, also known as T2, is a metabolite of thyroid hormone.

It is formed from the breakdown of triiodothyronine. It is an allosteric regulator of the cytochrome c oxidase, the complex IV of the electron transport chain. It increases its activity by preventing the interaction of adenosine triphosphate (ATP) as an allosteric inhibitor.[1]

Levels can be affected in certain disease states.[2]


Synthesis of T2 from T3, and from reverse T3


  1. ^ Arnold S., Goglia F., Kadenbach B. (1998). "3,5-Diiodothyronine binds to subunit Va of cytochrome-c oxidase and abolishes the allosteric inhibition of respiration by ATP.". Eur J Biochem. 252 (2): 325–330. doi:10.1046/j.1432-1327.1998.2520325.x. PMID 9523704. 
  2. ^ Pinna G, Hiedra L, Meinhold H, et al (September 1998). "3,3'-Diiodothyronine concentrations in the sera of patients with nonthyroidal illnesses and brain tumors and of healthy subjects during acute stress". J. Clin. Endocrinol. Metab. 83 (9): 3071–7. doi:10.1210/jc.83.9.3071. PMID 9745405.