| C15H13I2NO4|| 525.077 g/mol|
3,5-Diiodothyronine (3,5-T2) is an active thyroid hormone within the class of iodothyronines. It has two iodine atoms at positions 3 and 5 of its inner ring.
3,5-T2 is an active thyroid hormone. It stimulates the TR-beta receptor for thyroid hormones and thus increases energy expenditure. It has agonistic (thyromimetic) effects at myocardial tissue and pituitary, which results in 3,5-T2 to suppress TSH release. 3,5-T2 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.
In nonthyroidal illness syndrome 3,5-T2 concentrations are increased. This could explain why patients with low T3 syndrome don't benefit from substitution therapy with thyroid hormones.