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ENZYME

ENZYME entry: EC 1.21.99.4

PURL: https://purl.expasy.org/enzyme/EC/1.21.99.4
Accepted Name
thyroxine 5'-deiodinase
Alternative Name(s)
diiodothyronine 5'-deiodinase
iodothyronine 5'-deiodinase
iodothyronine outer ring monodeiodinase
L-thyroxine iodohydrolase (reducing)
thyroxine 5-deiodinase
type II iodothyronine deiodinase
type I iodothyronine deiodinase
Reaction catalysed
3,3',5-triiodo-L-thyronine + iodide + A + H(+) = L-thyroxine + AH2
Comment(s)
  • 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 1.97.1.10 and EC 3.8.1.4.
Cross-references
BRENDA1.21.99.4
EC2PDB1.21.99.4
ExplorEnz1.21.99.4
KEGG Ligand Database for Enzyme Nomenclature1.21.99.4
IUBMB Enzyme Nomenclature1.21.99.4
MEDLINEFind literature relating to 1.21.99.4
MetaCyc1.21.99.4
Rhea expert-curated reactions1.21.99.4
UniProtKB/Swiss-Prot
P49894, IOD1_CANLFO42411, IOD1_CHICKQ6V915, IOD1_FELCA
Q804E1, IOD1_FUNHEP49895, IOD1_HUMANQ61153, IOD1_MOUSE
O42449, IOD1_ORENIQ6QN13, IOD1_PIGA4GT88, IOD1_RABIT
P24389, IOD1_RATQ95N00, IOD1_SUNMUQ2QEI3, IOD1_XENLA
P49896, IOD2_AQUCTQ5I3B2, IOD2_BOVINQ9IAX2, IOD2_CHICK
P79747, IOD2_FUNHEQ92813, IOD2_HUMANQ9Z1Y9, IOD2_MOUSE
Q8UVX8, IOD2_NEOFSL7WGA7, IOD2_PETMAQ6QN12, IOD2_PIG
P70551, IOD2_RATQ6U6H1, IOD_HALRO

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