B₁₂ antivitamins are important and robust tools for investigating the biological roles of vitamin B₁₂. Here, the potential antivitamin B₁₂ 2,4‐difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co−C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B₁₂‐processing enzyme CblC with high affinity (K_D=130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B₁₂ and CblC, as well as into the organization of GSH and a base‐off cobalamin in the active site of this enzyme.

中文翻译：

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抗人维生素B12对人B12加工酶CblC的抑制作用：以谷胱甘肽为共底物的无活性三元复合物的晶体结构

B ₁₂抗维生素是研究维生素B ₁₂生物学作用的重要而强大的工具。在这里，制备了潜在的抗维生素B ₁₂ 2,4-二氟苯基乙炔基钴胺素（F2PhEtyCbl），并在溶液和晶体中研究了其3D结构。具有化学惰性的F2PhEtyCbl可以在100°C的温度下抵抗Co-C键的热解，在明亮的日光下稳定，并且在室温下长时间保存在水溶液中时也保持完整。它以高亲和力结合人B ₁₂加工酶CblC（K _D = 130 n m）在共底物谷胱甘肽（GSH）存在的情况下。F2PhEtyCbl抵御了CblC的剪裁，并且还稳定了GSH的三元复合物。这种失活的装配体的晶体结构提供了对维生素B ₁₂和CblC之间的结合相互作用的初步了解，以及对该酶活性位点中谷胱甘肽和碱式钴胺素的组织方式的初步了解。