Vitamin K-dependent carboxylation and vitamin K epoxidation. Evidence that the warfarin-sensitive microsomal NAD(P)H dehydrogenase reduces vitamin K1 in these reactions.
نویسندگان
چکیده
Passage of a Triton X-100-solubilized microsomal systems in vitro that are used to study these reactions is the warfarin-sensitive NAD(P)H dehydrogenase.
منابع مشابه
Functional study of the vitamin K cycle in mammalian cells.
We describe a cell-based assay for studying vitamin K-cycle enzymes. A reporter protein consisting of the gla domain of factor IX (amino acids 1-46) and residues 47-420 of protein C was stably expressed in HEK293 and AV12 cells. Both cell lines secrete carboxylated reporter when fed vitamin K or vitamin K epoxide (KO). However, neither cell line carboxylated the reporter when fed KO in the pres...
متن کاملAssessment of the contribution of NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) to the reduction of vitamin K in wild-type and NQO1-deficient mice.
NQO1 [NAD(P)H quinone oxidoreductase 1; also known as DT-diaphorase] is a cytosolic enzyme that catalyses the two-electron reduction of various quinones including vitamin K. The enzyme may play a role in vitamin K metabolism by reducing vitamin K to vitamin K hydroquinone for utilization in the post-translational γ-glutamyl carboxylation reactions required by several proteins involved in blood ...
متن کاملEvidence for the involvement of superoxide in vitamin K-dependent carboxylation of glutamic acid residues of prothrombin.
The formation of vitamin K epoxide and the vitamin K-dependent carboxylation of glutamic acid residues present in synthetic substrates and decarboxyprothrombin are both inhibited by superoxide dismutase. Catalase only inhibits the generation of vitamin K epoxide, suggesting that the carboxylation and epoxidation reactions are not inter-dependent.
متن کاملMicrosomal lipoamide reductase provides vitamin K epoxide reductase with reducing equivalents.
This study was undertaken to search for the endogenous dithiol cofactor of the reductases of the vitamin K cycle. As a starting point, the redox-active lipophilic endogenous compounds lipoic acid and lipoamide were looked at. The study shows that microsomes contain NADH-dependent lipoamide reductase activity. Reduced lipoamide stimulates microsomal vitamin K epoxide reduction with kinetics comp...
متن کاملThe inhibition of vitamin K-dependent carboxylase by cyanide.
The formation of 7-carboxyglutamic acid residues from glutamic acid residues is a vitamin K-dependent carboxylation reaction. The reaction has been demonstrated in various species and tissues [1,2], but the most extensive studies have been performed in the microsomal fraction of rat liver.It is generally assumed that the carboxylation reaction is coupled to the epoxidation of reduced vitamin K ...
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عنوان ژورنال:
- The Biochemical journal
دوره 194 3 شماره
صفحات -
تاریخ انتشار 1981