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EC 1.21.99.3 Details

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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

1.6.6 With a nitrogenous group as acceptor

1.6.6.1 created 1961, deleted 2002

1.6.6.2 created 1961, deleted 2002

1.6.6.3 created 1961, deleted 2002

1.6.6.4 created 1961, deleted 2002

1.6.6.5 created 1961, deleted 1964

1.6.6.6 created 1961, deleted 2002

1.6.6.7 created 1961, deleted 2002

1.6.6.8 created 1965, deleted 2002

1.6.6.9 trimethylamine-N-oxide reductase

1.6.6.10 created 1972, deleted 2002

1.6.6.11 created 1972, deleted 2002

1.6.6.12 created 1989, deleted 2002

1.6.6.13 created 1989, deleted 2002

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

1.23 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)

2 Transferases

3 Hydrolases

3.1 Acting on ester bonds

3.2 Glycosylases

3.3 Acting on ether bonds

3.4 Acting on peptide bonds (peptidases)

3.5 Acting on carbon-nitrogen bonds, other than peptide bonds

3.6 Acting on acid anhydrides

3.7 Acting on carbon-carbon bonds

3.8 Acting on halide bonds

3.9 Acting on phosphorus-nitrogen bonds

3.10 Acting on sulfur-nitrogen bonds

3.11 Acting on carbon-phosphorus bonds

3.12 Acting on sulfur-sulfur bonds

3.13 Acting on carbon-sulfur bonds