ExplorEnz: EC 1.11.1.8

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1.11.1.8

Accepted name:

iodide peroxidase

Reaction:

(1) 2 iodide + H₂O₂ + 2 H⁺ = diiodine + 2 H₂O
(2) [thyroglobulin]-L-tyrosine + iodide + H₂O₂ = [thyroglobulin]-3-iodo-L-tyrosine + 2 H₂O
(3) [thyroglobulin]-3-iodo-L-tyrosine + iodide + H₂O₂ = [thyroglobulin]-3,5-diiodo-L-tyrosine + 2 H₂O
(4) 2 [thyroglobulin]-3,5-diiodo-L-tyrosine + H₂O₂ = [thyroglobulin]-L-thyroxine + [thyroglobulin]-aminoacrylate + 2 H₂O
(5) [thyroglobulin]-3-iodo-L-tyrosine + [thyroglobulin]-3,5-diiodo-L-tyrosine + H₂O₂ = [thyroglobulin]-3,5,3′-triiodo-L-thyronine + [thyroglobulin]-aminoacrylate + 2 H₂O

Glossary:

3,5,3′-triiodo-L-thyronine = triiodo-L-thyronine

Other name(s):

thyroid peroxidase; iodoperoxidase (heme type); iodide peroxidase-tyrosine iodinase; thyroperoxidase; tyrosine iodinase; TPO; iodinase

Systematic name:

iodide:hydrogen-peroxide oxidoreductase

Comments:

Thyroid peroxidase catalyses the biosynthesis of the thyroid hormones L-thyroxine and triiodo-L-thyronine. It catalyses both the iodination of tyrosine residues in thyroglobulin (forming mono- and di-iodinated forms) and their coupling to form either L-thyroxine or triiodo-L-thyronine.

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9031-28-1

References:

1.	Cunningham, B.A. and Kirkwood, S. Enzyme systems concerned with the synthesis of monoiodotyrosine. III. Ion requirements of the soluble system. J. Biol. Chem. 236 (1961) 485–489. [PMID: 13718859]
2.	Hosoya, T., Kondo, Y. and Ui, N. Peroxidase activity in thyroid gland and partial purification of the enzyme. J. Biochem. (Tokyo) 52 (1962) 180–189. [PMID: 13964156]
3.	Coval, M.L. and Taurog, A. Purification and iodinating activity of hog thyroid peroxidase. J. Biol. Chem. 242 (1967) 5510–5523. [PMID: 12325367]
4.	Gavaret, J.M., Cahnmann, H.J. and Nunez, J. Thyroid hormone synthesis in thyroglobulin. The mechanism of the coupling reaction. J. Biol. Chem. 256 (1981) 9167–9173. [PMID: 7021557]
5.	Ohtaki, S., Nakagawa, H., Nakamura, M. and Yamazaki, I. One- and two-electron oxidations of tyrosine, monoiodotyrosine, and diiodotyrosine catalyzed by hog thyroid peroxidase. J. Biol. Chem. 257 (1982) 13398–13403. [PMID: 7142155]
6.	Magnusson, R.P., Taurog, A. and Dorris, M.L. Mechanism of iodide-dependent catalatic activity of thyroid peroxidase and lactoperoxidase. J. Biol. Chem. 259 (1984) 197–205. [PMID: 6706930]
7.	Virion, A., Courtin, F., Deme, D., Michot, J.L., Kaniewski, J. and Pommier, J. Spectral characteristics and catalytic properties of thyroid peroxidase-H₂O₂ compounds in the iodination and coupling reactions. Arch. Biochem. Biophys. 242 (1985) 41–47. [DOI] [PMID: 2996435]
8.	Rawitch, A.B., Pollock, G., Yang, S.X. and Taurog, A. Thyroid peroxidase glycosylation: the location and nature of the N-linked oligosaccharide units in porcine thyroid peroxidase. Arch. Biochem. Biophys. 297 (1992) 321–327. [DOI] [PMID: 1497352]
9.	Sun, W. and Dunford, H.B. Kinetics and mechanism of the peroxidase-catalyzed iodination of tyrosine. Biochemistry 32 (1993) 1324–1331. [PMID: 8448141]
10.	Taurog, A., Dorris, M.L. and Doerge, D.R. Mechanism of simultaneous iodination and coupling catalyzed by thyroid peroxidase. Arch. Biochem. Biophys. 330 (1996) 24–32. [DOI] [PMID: 8651700]
11.	Ruf, J. and Carayon, P. Structural and functional aspects of thyroid peroxidase. Arch. Biochem. Biophys. 445 (2006) 269–277. [DOI] [PMID: 16098474]

[EC 1.11.1.8 created 1961, modified 2012]