EC - Thyroxine 5'-deiodinase

  IntEnz view ENZYME view

IntEnz Enzyme Nomenclature


Accepted name:
thyroxine 5'-deiodinase
Other names:
L-thyroxine iodohydrolase (reducing)
diiodothyronine 5'-deiodinase [ambiguous]
iodothyronine 5'-deiodinase
iodothyronine outer ring monodeiodinase
thyroxine 5-deiodinase [misleading]
type I iodothyronine deiodinase
type II iodothyronine deiodinase
Systematic name:
3,3',5-triiodo-L-thyronine,iodide:acceptor oxidoreductase (iodinating)



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. Formerly EC and EC

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00172 , PROSITE:PDOC00925
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004800
CAS Registry Number: 70712-46-8
UniProtKB/Swiss-Prot: (33) [show] [UniProt]


  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 : 89-97 (1982). [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 : 1231-1238 (1982). [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 : 2336-2345 (1981). [PMID: 7227308]
  4. Köhrle, J.
    Iodothyronine deiodinases.
    Methods Enzymol. 347 : 125-167 (2002). [PMID: 11898402]

[EC created 1984 as EC, transferred 2003 to EC, transferred 2015 to EC]