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  • Title: Vitamin K-dependent carboxylation. Evidence that at least two microsomal dehydrogenases reduce vitamin K1 to support carboxylation.
    Author: Wallin R, Hutson S.
    Journal: J Biol Chem; 1982 Feb 25; 257(4):1583-6. PubMed ID: 6799508.
    Abstract:
    It has been shown that NAD(P)H dehydrogenase (EC 1.6.99.2) reduces vitamin K1 and can support the [vitamin K1 + NADH]-dependent carboxylation reaction in rat liver microsomes (Wallin, R., Gebhardt, O., and Prydz, H. (1978) Biochem. J. 169, 95-101). Antibodies were raised in rabbits against the purified enzyme from liver cytosol and used to study the importance of NAD(P)H dehydrogenase in the vitamin K-dependent carboxylation reaction. The antibodies neutralized the warfarin-sensitive NAD(P)H dehydrogenase activity in Triton X-100-solubilized microsomes; however, they neutralized only 45% of the total [vitamin K1 + NADH]-dependent carboxylation activity. Chromatography on protein A-sepharose showed that the remaining carboxylase activity was not the result of soluble antigen-antibody complexes. The data presented support the conclusion that the microsomal preparation also contains a non-warfarin-sensitive dehydrogenase(s) that, in addition to NAD(P)H dehydrogenase, can reduce vitamin K1 to support the carboxylation reaction.
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