What is the Origin of Thyroid Peroxidase Function?

This term is a fundamental concept in thyroid endocrinology and biochemistry, derived from the discovery and characterization of the enzyme responsible for the organification of iodine. Thyroid Peroxidase is named for its location and its function as an enzyme that catalyzes an oxidation reaction. Clinical relevance grew significantly with the identification of TPO antibodies as a primary diagnostic marker for Hashimoto's thyroiditis, an autoimmune condition.

What is the Mechanism of Thyroid Peroxidase Function?

The mechanism involves TPO utilizing hydrogen peroxide to oxidize iodide ions, which are actively transported into the follicular cell, converting them into a reactive iodine species. This reactive iodine then attaches to tyrosine residues on the thyroglobulin protein, a process called organification. Subsequently, TPO catalyzes the coupling of two iodinated tyrosine molecules—Monoiodotyrosine (MIT) or Diiodotyrosine (DIT)—to form the final thyroid hormones, T4 and T3, which are then stored until secretion.

Thyroid Peroxidase Function ∞ Area

Thyroid Peroxidase Function

Meaning

Thyroid Peroxidase (TPO) Function refers to the enzymatic activity of the TPO protein, which is critically responsible for the key steps in thyroid hormone synthesis within the thyroid follicular cells. This enzyme catalyzes both the iodination of thyroglobulin and the coupling of iodotyrosines to form the active hormones, thyroxine (T4) and triiodothyronine (T3). Impaired TPO function, often due to autoimmune attack by TPO antibodies, is a common clinical cause of thyroid dysfunction and hypothyroidism.