Anti-thyroid peroxidase
Thyroid peroxidase, also called thyroperoxidase (TPO) or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T4) or triiodothyronine (T3), the thyroid hormones. In humans, thyroperoxidase is encoded by the TPO gene.
+ I− + H+ + H2O2 ⇒ + 2 H2O
Iodide is oxidized to iodine radical which immediately reacts with tyrosine.
+ I− + H+ + H2O2 ⇒ + 2 H2O
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