Biomaterial Database

Differential effects of methylmercuric chloride and mercuric chloride on oxidation and iodination reactions catalyzed by thyroid peroxidase. 1990

M Nishida, and K Sato, and J Kawada

Faculty of Pharmaceutical Sciences, University of Tokushima, Shomachi, Japan.

Thyroid peroxidase (TPO), the major enzyme in the thyroid hormone synthesis, multifunctionally catalyzes (1) iodide oxidation, (2) iodination of the precursor protein, and (3) a coupling reaction of iodotyrosyl residues. The present study was carried out to examine the mercurial effects on the iodination, the second step of TPO. Purified porcine thyroglobulin or bovine serum albumin as acceptor protein was iodinated with [125I]NaI and H2O2 by purified porcine TPO. Iodinated protein was separated by acid precipitation on membrane filter or paper chromatography. Both CH3HgCl and HgCl2 dose-dependently inhibited the iodination, but HgCl2 was more potent to inhibit the iodination than CH3HgCl. These mercurial effects on the second step resemble the effects on the third step which were already reported; but are in marked contrast to the effects on the first step, where TPO was inhibited by HgCl2 but never by CH3HgCl.

UI	MeSH Term	Description	Entries
D007453	Iodide Peroxidase	A hemeprotein that catalyzes the oxidation of the iodide radical to iodine with the subsequent iodination of many organic compounds, particularly proteins. EC 1.11.1.8.	Iodinase,Iodothyronine 5'-Deiodinase,Iodothyronine Deiodinase,Iodotyrosine Deiodase,Thyroid Peroxidase,Thyroxine 5'-Deiodinase,Thyroxine 5'-Monodeiodinase,5'-Deiodinase,Deiodinase,Iodotyrosine Deiodinase,Monodeiodinase,Reverse Triiodothyronine 5'-Deiodinase,T4-5'-Deiodinase,T4-Monodeiodinase,Tetraiodothyronine 5'-Deiodinase,Thyroxine Converting Enzyme,Triiodothyronine Deiodinase,5' Deiodinase,5'-Deiodinase, Iodothyronine,5'-Deiodinase, Reverse Triiodothyronine,5'-Deiodinase, Tetraiodothyronine,5'-Deiodinase, Thyroxine,5'-Monodeiodinase, Thyroxine,Deiodase, Iodotyrosine,Deiodinase, Iodothyronine,Deiodinase, Iodotyrosine,Deiodinase, Triiodothyronine,Enzyme, Thyroxine Converting,Iodothyronine 5' Deiodinase,Peroxidase, Iodide,Peroxidase, Thyroid,Reverse Triiodothyronine 5' Deiodinase,T4 5' Deiodinase,T4 Monodeiodinase,Tetraiodothyronine 5' Deiodinase,Thyroxine 5' Deiodinase,Thyroxine 5' Monodeiodinase,Triiodothyronine 5'-Deiodinase, Reverse
D007455	Iodine	A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126.90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically.	Iodine-127,Iodine 127
D007457	Iodine Radioisotopes	Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.	Radioisotopes, Iodine
D008627	Mercuric Chloride	Mercury chloride (HgCl2). A highly toxic compound that volatizes slightly at ordinary temperature and appreciably at 100 degrees C. It is corrosive to mucous membranes and used as a topical antiseptic and disinfectant.	Mercury Dichloride,Corrosive Sublimate,HgCl2,Mercuric Perchloride,Mercury Bichloride,Mercury Perchloride,Sublimate,Bichloride, Mercury,Chloride, Mercuric,Dichloride, Mercury,Perchloride, Mercuric,Perchloride, Mercury,Sublimate, Corrosive
D008767	Methylmercury Compounds	Organic compounds in which mercury is attached to a methyl group.	Methyl Mercury Compounds,Compounds, Methyl Mercury,Compounds, Methylmercury,Mercury Compounds, Methyl
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D006861	Hydrogen Peroxide	A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.	Hydrogen Peroxide (H2O2),Hydroperoxide,Oxydol,Perhydrol,Superoxol,Peroxide, Hydrogen
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012709	Serum Albumin	A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.	Plasma Albumin,Albumin, Serum
D012974	Sodium Iodide	A compound forming white, odorless deliquescent crystals and used as iodine supplement, expectorant or in its radioactive (I-131) form as an diagnostic aid, particularly for thyroid function tests.