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A hetero-dimer model for concerted action of vitamin K carboxylase and vitamin K reductase in vitamin K cycle |
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| Authors: | Wu Sangwook Liu Shubin Davis Charles H Stafford Darrel W Kulman John D Pedersen Lee G |
| Affiliation: | a Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA b Division of Research Computing, Information Technology Services, University of North Carolina, Chapel Hill, NC 27599-3455, USA c Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, USA d Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA e Division of Hematology, University of Washington School of Medicine, 921 Terry Avenue, Seattle, WA 98104-1256, USA |
| Abstract: | Vitamin K carboxylase (VKC) is believed to convert vitamin K, in the vitamin K cycle, to an alkoxide-epoxide form which then reacts with CO2 and glutamate to generate γ-carboxyglutamic acid (Gla). Subsequently, vitamin K epoxide reductase (VKOR) is thought to convert the alkoxide-epoxide to a hydroquinone form. By recycling vitamin K, the two integral-membrane proteins, VKC and VKOR, maintain vitamin K levels and sustain the blood coagulation cascade. Unfortunately, NMR or X-ray crystal structures of the two proteins have not been characterized. Thus, our understanding of the vitamin K cycle is only partial at the molecular level. In this study, based on prior biochemical experiments on VKC and VKOR, we propose a hetero-dimeric form of VKC and VKOR that may explain the efficient oxidation and reduction of vitamin K during the vitamin K cycle. |
| Keywords: | Vitamin K cycle Vitamin K carboxylase Vitamin K epoxide reductase Hetero-dimer |
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