Characteristics of rT3 5'-monodeiodination in rat brain: comparison with T4 and T3 5-monodeiodinations
- 1 November 1982
- journal article
- research article
- Published by Bioscientifica in Acta Endocrinologica
- Vol. 101 (3) , 371-376
- https://doi.org/10.1530/acta.0.1010371
Abstract
The present study revealed the existence and some characteristics of rT3 5'-deiodinase in rat brain by measuring the production of 3,3'-T2 from rT3 by radioimmunoassay. The conversion of rT3 to 3,3'-T2 was dependent on the duration of the incubation, tissue amount, temperature and pH (the optimal pH was 8.0), suggesting its enzymatic nature. Apparent Km was estimated to be 0.16 μm and the Vmax was 139.3 fmol/mg protein/min. The converting activity was dependent on the concentration of dithiothreitol (DTT). In contrast to T4 or T3 5-deiodinase, rT3 5'-deiodinase activity in the rat brain was the highest in cerebellum and the activity was low in the neonatal rat brain. Moreover, the 5'-deiodinase activity was inhibited by propylthiouracil (PTU). These differences between rT3 5'-deiodinase and T4 or T3 5-deiodinase suggest that different deiodinases are present in rat brain, and that local conversion of thyroid hormone is important for its action in the central nervous system.This publication has 13 references indexed in Scilit:
- Maturational Patterns of Iodothyronine Phenolic and Tyrosyl Ring Deiodinase Activities in Rat Cerebrum, Cerebellum, and HypothalamusJournal of Clinical Investigation, 1981
- Age-Related Changes of Serum 3,3′-Diiodothyronine, 3′,5′-Diiodothyronine, and 3,5-Diiodothyronine Concentrations in ManJournal of Clinical Endocrinology & Metabolism, 1981
- Phenolic and Tyrosyl Ring Deiodination of Iodothyronines in Rat Brain HomogenatesJournal of Clinical Investigation, 1980
- The Role of Sulfhydryl Groups on the Impaired Hepatic 3′,3,5-Triiodothyronine Generation from Thyroxine in the Hypothyroid, Starved, Fetal, and Neonatal RodentJournal of Clinical Investigation, 1979
- Uptake and Metabolism of Exogenous and Endogenous Thyroxine in the Brain of Young RatsHormone and Metabolic Research, 1979
- Thyroxine 5′-Deiodinase Activity of Rat Kidney: Observations on Activation by Thiols and Inhibition by Propylthiouracil*Endocrinology, 1978
- Monodeiodination of 3,5,3′-Triiodothyronine and 3,3′,5′- Triiodothyronine to 3,3′-Diiodothyroninein Vitro*Endocrinology, 1978
- Sulfhydryl Groups and the Monodeiodination of Thyroxine to TriiodothyronineScience, 1978
- Subcellular localization of a rat liver enzyme converting thyroxine into tri-iodothyronine and possible involvement of essential thiol groupsBiochemical Journal, 1976
- PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENTJournal of Biological Chemistry, 1951