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Updated: Aug 19, 2026

Fast and Specific Assessment of the Halogenating Peroxidase Activity in Leukocyte-enriched Blood Samples
Published on: July 28, 2016
Gastric peroxidase--localization, catalytic properties and possible role in extrathyroidal thyroid hormone formation
Abstract:
A highly active peroxidase (EC 1.11.1.7) has been found to be localized in the mitochondria isolated from the fundic region of mouse stomach. The stomach has also the property of concentrating iodide significantly. Evidence has been presented to show that the peroxidase is orientated outside the mitochondrial membrane. The enzyme is strongly inhibited by antithyroid drugs like methimazole and thiouracil. Azide and cyanide completely inactivate the enzyme. The activity is inhibited by SH-blocking reagents like mersalyl or p-chloromercuribenzene sulphonate, but not by N-ethyl-maleimide. The enzyme is also sensitive to the action of some proteolytic enzymes. It can catalyse the formation of mono- or diiodotyrosine from tyrosine or monoiodotyrosine as substrate, respectively. The enzyme is capable of synthesizing thyroxine and triiodothyronine on the backbone of a protein, such as thyroglobulin or albumin.
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