Boron Cluster-based Development of Potent Nonsecosteroidal Vitamin D Receptor Ligands: Direct Observation of Hydrophobic Interaction between Protein Surface and Carborane

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• 作者：Shinya Fujii ; Hiroyuki Masuno ; Yoshiyuki Taoda ; Atsushi Kano ; Angsuma Wongmayura ; Makoto Nakabayashi ; Nobutoshi Ito ; Masato Shimizu ; Emiko Kawachi ; Tomoya Hirano ; Yasuyuki Endo ; Aya Tanatani ; Hiroyuki Kagechika
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：December 28, 2011
• 年：2011
• 卷：133
• 期：51
• 页码：20933-20941
• 全文大小：962K
• 年卷期：v.133,no.51(December 28, 2011)
• ISSN：1520-5126

文摘

We report here the design and synthesis of a novel vitamin D receptor (VDR) agonist whose hydrophobic core structure is p-carborane (1,12-dicarba-closo-dodecaborane, an icosahedral carbon-containing boron cluster having remarkable thermal and chemical stability and a characteristically hydrophobic B鈥揌 surface). This carborane-based VDR ligand exhibited moderate vitamin D activity, comparable to that of the natural hormone, despite its simple and flexible structure. X-ray structure analysis provided direct evidence that the carborane cage binds to the hydrophobic surface of the ligand-binding pocket of the receptor, promoting transition to the active conformation. These results indicate that the spherical B鈥揌 surface of carborane can function efficiently as a hydrophobic anchor in binding to the receptor surface, thereby allowing induced fitting of the three essential hydroxyl groups on the alkyl chains to the appropriate positions for interaction with the VDR binding site, despite the entropic disadvantage of the flexible structure. We suggest that carborane structure is a promising option in the design of novel drug candidates.