Which enzyme is essential for iodination in thyroid hormone synthesis?

Which enzyme is essential for iodination in thyroid hormone synthesis?

• A. Thyroid peroxidase
• B. Thyroglobulin
• C. Deiodinase
• D. TSH

Answer: (A)

The enzyme that directly enables iodination in thyroid hormone synthesis is thyroid peroxidase. It catalyzes the oxidation of iodide to reactive iodine and attaches it to tyrosine residues on thyroglobulin, forming MIT and DIT. These iodinated tyrosines then couple to produce the thyroid hormones T3 and T4. Without this enzyme, iodination cannot occur, so hormone synthesis stalls. Thyroglobulin provides the scaffold for iodination, deiodinase removes iodine in peripheral tissues, and TSH regulates thyroid activity but does not perform the iodination step.

The enzyme that directly enables iodination in thyroid hormone synthesis is thyroid peroxidase. It catalyzes the oxidation of iodide to reactive iodine and attaches it to tyrosine residues on thyroglobulin, forming MIT and DIT. These iodinated tyrosines then couple to produce the thyroid hormones T3 and T4. Without this enzyme, iodination cannot occur, so hormone synthesis stalls. Thyroglobulin provides the scaffold for iodination, deiodinase removes iodine in peripheral tissues, and TSH regulates thyroid activity but does not perform the iodination step.