By using a highly specific radioimmunoassay the formation of tri-iodothyronine by the deiodination of thyroxine was studied in rat liver homogenate. Several observations suggest that the reaction observed is enzymic in nature. Pre-heating the homogenate for 30 min at 56 degrees C completely abolished conversion of thyroxine into tri-iodothyronine; the component of rat liver homogenate responsible could be saturated with substrate; iodotyrosines displayed competitive activity. Between 0 degrees and 37 degrees C, the tri-iodothyronine-production rate was positively correlated with incubation temperature. The addition of NAD+ enhanced conversion into tri-iodothyronine, which suggests that an oxidative mechanism is involved. 5-Propyl-2-thiouracil and 6-propyl-2-thiouracil, both known to prevent deiodination in vivo, greatly decreased the deiodiantion activity of rat liver homogenate.
Skip Nav Destination
Research Article| September 01 1975
Conversion of thyroxine into tri-iodothyronine by rat liver homogenate
Theo J Visser;
Ineke Van Der Does-Tobé;
Biochem J (1975) 150 (3): 489–493.
- Views Icon Views
- Share Icon Share
Theo J Visser, Ineke Van Der Does-Tobé, Roel Docter, Georg Hennemann; Conversion of thyroxine into tri-iodothyronine by rat liver homogenate. Biochem J 1 September 1975; 150 (3): 489–493. doi: https://doi.org/10.1042/bj1500489
Download citation file: