EC |
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, 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] |
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[EC 1.11.1.8 created 1961, modified 2012] |
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EC |
1.21.99.3 |
Accepted name: |
thyroxine 5-deiodinase |
Reaction: |
3,3′,5′-triiodo-L-thyronine + iodide + acceptor + H+ = L-thyroxine + reduced acceptor |
Other name(s): |
diiodothyronine 5′-deiodinase (ambiguous); iodothyronine 5-deiodinase; iodothyronine inner ring monodeiodinase; type III iodothyronine deiodinase |
Systematic name: |
3,3′,5′-triiodo-L-thyronine,iodide:acceptor oxidoreductase (iodinating) |
Comments: |
The enzyme activity has only been demonstrated in the direction of 5-deiodination. This removal of the 5-iodine, i.e. from the inner ring, largely inactivates the hormone thyroxine. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 74506-30-2 |
References: |
1. |
Chopra, I.J. and Teco, G.N.C. Characteristics of inner ring (3 or 5) monodeiodination of 3,5-diiodothyronine in rat liver: evidence suggesting marked similarities of inner and outer ring deiodinases for iodothyronines. Endocrinology 110 (1982) 89–97. [DOI] [PMID: 7053997] |
2. |
Körhle, J. Iodothyronine deiodinases. Methods Enzymol. 347 (2002) 125–167. [PMID: 11898402] |
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[EC 1.21.99.3 created 2003 as EC 1.97.1.11, transferred 2015 to EC 1.21.99.3] |
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EC |
1.21.99.4 |
Accepted name: |
thyroxine 5′-deiodinase |
Reaction: |
3,3′,5-triiodo-L-thyronine + iodide + acceptor + H+ = L-thyroxine + reduced acceptor |
Glossary: |
3,3′,5-triiodo-L-thyronine = O-(4-hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine
L-thyroxine = O-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-L-tyrosine |
Other name(s): |
diiodothyronine 5′-deiodinase [ambiguous]; iodothyronine 5′-deiodinase; iodothyronine outer ring monodeiodinase; type I iodothyronine deiodinase; type II iodothyronine deiodinase; thyroxine 5-deiodinase [misleading]; L-thyroxine iodohydrolase (reducing) |
Systematic name: |
3,3′,5-triiodo-L-thyronine,iodide:acceptor oxidoreductase (iodinating) |
Comments: |
The enzyme activity has only been demonstrated in the direction of 5′-deiodination, which renders the thyroid hormone more active. The enzyme consists of type I and type II enzymes, both containing selenocysteine, but with different kinetics. For the type I enzyme the first reaction is a reductive deiodination converting the -Se-H group of the enzyme into an -Se-I group; the reductant then reconverts this into -Se-H, releasing iodide. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 70712-46-8 |
References: |
1. |
Chopra, I.J. and Teco, G.N.C. Characteristics of inner ring (3 or 5) monodeiodination of 3,5-diiodothyronine in rat liver: evidence suggesting marked similarities of inner and outer ring deiodinases for iodothyronines. Endocrinology 110 (1982) 89–97. [DOI] [PMID: 7053997] |
2. |
Goswani, A., Leonard, J.L. and Rosenberg, I.N. Inhibition by coumadin anticoagulants of enzymatic outer ring monodeiodination of iodothyronines. Biochem. Biophys. Res. Commun. 104 (1982) 1231–1238. [DOI] [PMID: 6176242] |
3. |
Smallridge, R.C., Burman, K.D., Ward, K.E., Wartofsky, L., Dimond, R.C., Wright, F.D. and Lathan, K.R. 3′,5′-Diiodothyronine to 3′-monoiodothyronine conversion in the fed and fasted rat: enzyme characteristics and evidence for two distinct 5′-deiodinases. Endocrinology 108 (1981) 2336–2345. [DOI] [PMID: 7227308] |
4. |
Körhle, J. Iodothyronine deiodinases. Methods Enzymol. 347 (2002) 125–167. [PMID: 11898402] |
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[EC 1.21.99.4 created 1984 as EC 3.8.1.4, transferred 2003 to EC 1.97.1.10, transferred 2015 to EC 1.21.99.4] |
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EC
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1.97.1.10
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Transferred entry: | thyroxine 5′-deiodinase. Now EC 1.21.99.4 thyroxine 5′-deiodinase
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[EC 1.97.1.10 created 1984 as EC 3.8.1.4, transferred 2003 to EC 1.97.1.10, deleted 2015] |
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EC
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1.97.1.11
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Transferred entry: | thyroxine 5-deiodinase. Now EC 1.21.99.3 thyroxine 5-deiodinase.
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[EC 1.97.1.11 created 2003, deleted 2015] |
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