Related Experiment Video
Updated: Jul 6, 2026

Colorimetric Assessment of Deiodinase 1 Activity in Human Liver Microsomes Using the Sandell-Kolthoff Reaction
Published on: April 10, 2026
Iodothyronine deiodinase
1Donald L. St. Germain is at the Departments of Medicine and Physiology, Dartmouth Medical School, Lebanon, NH 03756, USA.
The iodothyronine deiodinases constitute a family of enzymes that catalyze the removal of iodine atoms from various thyroid hormones (THs) in the thyroid gland and extrathyroidal tissues. As such, they are responsible for both the activation and inactivation of these compounds, and are thus important regulators of TH action. Recently, new insights have been gained into the biochemical characteristics of these proteins and their physiologic roles in TH metabolism. In particular, the availability of affinity-labeling techniques, molecular probes, and specific antisera for these enzymes, and the recent identification of the type I deiodinase as a selenoprotein, have ushered in a new era in the study of thyroid hormone deiodination.
The iodothyronine deiodinases constitute a family of enzymes that catalyze the removal of iodine atoms from various thyroid hormones (THs) in the thyroid gland and extrathyroidal tissues. As such, they are responsible for both the activation and inactivation of these compounds, and are thus important regulators of TH action. Recently, new insights have been gained into the biochemical characteristics of these proteins and their physiologic roles in TH metabolism. In particular, the availability of affinity-labeling techniques, molecular probes, and specific antisera for these enzymes, and the recent identification of the type I deiodinase as a selenoprotein, have ushered in a new era in the study of thyroid hormone deiodination.
Related Concept Videos
Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Functions of Thyroid Hormones
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Hyperthyroidism II: Pathophysiology
Hypothyroidism II: Pathophysiology
Hyperthyroidism I: Introduction
Graves Disease II: Pathophysiology

