Developmental changes of vitamin K epoxidase and reductase activities involved in the vitamin K cycle in human liver.
We examined the developmental changes in activities of vitamin K epoxidase, and vitamin K-2,3-epoxide reductase and vitamin K reductase in the human autopsied liver. The activity of epoxidase, which converts vitamin K hydroquinone to its epoxide, showed a high value in the early prenatal period of 10-30 gestational weeks but decreased rather rapidly in contrast with the reductase activities. After birth, a significant decrease of the epoxidase activity was observed but no such change was seen during the postnatal period. On the other hand, the activities of vitamin K-2,3-epoxide reductase and vitamin K reductase, which convert vitamin K-2,3-epoxide to its hydroquinone, showed a significantly low value in the early prenatal period. The highest activity of vitamin K epoxidase in the early prenatal period may be essential to the production of vitamin K dependent ligands for growth factors expressed in the embryo.
Itoh
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Department of Pediatrics, Kagawa Medical University, Miki, Kitagun, Japan.
Onishi
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D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008099:Liver / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism*; D011247:Pregnancy; D014812:Vitamin K / Q000378:metabolism*; D064417:Vitamin K Epoxide Reductases
D014812:Vitamin K; D006899:Mixed Function Oxygenases; D064417:Vitamin K Epoxide Reductases; D016660:NAD(P)H Dehydrogenase (Quinone)