EC Explorer

[browse EC tree] - [search]

EC 1.21.99.3 Details

show Brenda entry

EC number

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)

CAS registry number

74506-30-2

Comment

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.

History

created 2003 as EC 1.97.1.11, transferred 2015 to EC 1.21.99.3

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.2 Acting on the aldehyde or oxo group of donors

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.6.1 With NAD⁺ or NADP⁺ as acceptor

1.6.2 With a heme protein as acceptor

1.6.3 With oxygen as acceptor

1.6.4 With a disulfide as acceptor (deleted sub-subclass)

1.6.5 With a quinone or similar compound as acceptor

1.6.5.1 created 1961, deleted 1965

1.6.5.2 NAD(P)H dehydrogenase (quinone)

1.6.5.3 NADH:ubiquinone reductase (H⁺-translocating)

1.6.5.4 monodehydroascorbate reductase (NADH)

1.6.5.5 NADPH:quinone reductase

1.6.5.6 p-benzoquinone reductase (NADPH)

1.6.5.7 2-hydroxy-1,4-benzoquinone reductase

1.6.5.8 NADH:ubiquinone reductase (Na⁺-transporting)

1.6.5.9 NADH:quinone reductase (non-electrogenic)

1.6.5.10 NADPH dehydrogenase (quinone)

1.6.5.11 NADH dehydrogenase (quinone)

1.6.5.12 demethylphylloquinone reductase

1.6.6 With a nitrogenous group as acceptor

1.6.7 With an iron-sulfur protein as acceptor (deleted sub-subclass)

1.6.8 With a flavin as acceptor (deleted sub-subclass)

1.6.99 With unknown physiological acceptors

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.11.1 Peroxidases

1.11.2 Peroxygenases

1.12 Acting on hydrogen as donor

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.99 With unknown physiological acceptors

1.21.99.1 β-cyclopiazonate dehydrogenase

1.21.99.2 cyclic dehypoxanthinyl futalosine synthase

1.21.99.3 thyroxine 5-deiodinase

1.21.99.4 thyroxine 5′-deiodinase

1.21.99.5 tetrachloroethene reductive dehalogenase

1.22 Acting on halogen in donors

1.22.1 With NAD⁺ or NADP⁺ as acceptor

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)