IUBMB Enzyme Nomenclature

EC 1.17.4.4

Accepted name: vitamin-K-epoxide reductase (warfarin-sensitive)

Reaction: phylloquinone + oxidized dithiothreitol + H2O = 2,3-epoxy-2-methyl-3-phytyl-2,3-dihydro-1,4-naphthoquinone + 1,4-dithiothreitol

For diagram of reaction click here.

Glossary: phylloquinone = 2-methyl-3-phytyl-1,4-naphthoquinone
2,3-epoxy-2-methyl-3-phytyl-2,3-dihydro-1,4-naphthoquinone = vitamin K 2,3-epoxide

Systematic name: phylloquinone:oxidized-dithiothreitol oxidoreductase

Comments: Vitamin K 2,3-epoxide is reduced to vitamin K and possibly to vitamin K hydroquinone by 1,4-dithiothreitol, which is oxidized to a disulfide; some other dithiols and 4-butanethiol can also act. Inhibited strongly by warfarin [cf. EC 1.17.4.5, vitamin-K-epoxide reductase (warfarin-insensitive)].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Lee, J.L. and Fasco, M.J. Metabolism of vitamin K and vitamin K 2,3-epoxide via interaction with a common disulfide. Biochemistry 23 (1984) 2246-2252. [PMID: 6733086]

2. Mukharji, I. and Silverman, R.B. Purification of a vitamin K epoxide reductase that catalyzes conversion of vitamin K 2,3-epoxide to 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone. Proc. Natl. Acad. Sci. USA 82 (1985) 2713-2717. [PMID: 3857611]

3. Whitlon, D.S., Sadowski, J.A. and Suttie, J.W. Mechanism of coumarin action: significance of vitamin K epoxide reductase inhibition. Biochemistry 17 (1978) 1371-1377. [PMID: 646989]

[EC 1.17.4.4 created 1989 as 1.1.4.1, transferred 2014 to EC 1.17.4.4]


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