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EC 1.17.4.4 Details

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EC number

1.17.4.4

Accepted name

vitamin-K-epoxide reductase (warfarin-sensitive)

Reaction

(1) phylloquinone + a protein with a disulfide bond + H₂O = 2,3-epoxyphylloquinone + a protein with reduced L-cysteine residues;;(2) phylloquinol + a protein with a disulfide bond = phylloquinone + a protein with reduced L-cysteine residues

Other name(s)

VKORC1 (gene name), VKORC1L1 (gene name)

Systematic name

phylloquinone:disulfide oxidoreductase

CAS registry number

55963-40-1

Comment

The enzyme catalyses the reduction of vitamin K 2,3-epoxide, which is formed by the activity of EC 4.1.1.90, peptidyl-glutamate 4-carboxylase, back to its phylloquinol active form. The enzyme forms a tight complex with EC 5.3.4.1, protein disulfide-isomerase, which transfers the required electrons from newly-synthesized proteins by catalysing the formation of disulfide bridges. The enzyme acts on the epoxide forms of both phylloquinone (vitamin K₁) and menaquinone (vitamin K₂). Inhibited strongly by (S)-warfarin and ferulenol.

History

created 1989 as EC 1.1.4.1, transferred 2014 to EC 1.17.4.4, modified 2018

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

1.7 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

1.12 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

1.17.1 With NAD⁺ or NADP⁺ as acceptor

1.17.2 With a cytochrome as acceptor

1.17.3 With oxygen as acceptor

1.17.4 With a disulfide as acceptor

1.17.4.1 ribonucleoside-diphosphate reductase

1.17.4.2 ribonucleoside-triphosphate reductase (thioredoxin)

1.17.4.3 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase

1.17.4.4 vitamin-K-epoxide reductase (warfarin-sensitive)

1.17.4.5 vitamin-K-epoxide reductase (warfarin-insensitive)

1.17.5 With a quinone or similar compound as acceptor

1.17.7 With an iron-sulfur protein as acceptor

1.17.8 With a flavin as acceptor

1.17.9 With a copper protein as acceptor

1.17.98 With other, known, physiological acceptors

1.17.99 With unknown physiological acceptors

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

1.20.1 With NAD⁺ or NADP⁺ as acceptor

1.20.2 With a cytochrome as acceptor

1.20.4 With disulfide as acceptor

1.20.9 With a copper protein as acceptor

1.20.98 With other, known, physiological acceptors

1.20.99 With unknown physiological acceptors

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

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

2.1 Transferring one-carbon groups

2.2 Transferring aldehyde or ketonic groups

2.3 Acyltransferases

2.4 Glycosyltransferases

2.5 Transferring alkyl or aryl groups, other than methyl groups

2.6 Transferring nitrogenous groups

2.7 Transferring phosphorus-containing groups

2.8 Transferring sulfur-containing groups

2.9 Transferring selenium-containing groups

2.10 Transferring molybdenum- or tungsten-containing groups