Drug binding in cardiac calcium channels : Identification and its application to drug development

心脏钙通道中的药物结合：鉴定及其在药物开发中的应用

• 批准号: 08044306
• 负责人: NAKAYAMA Hitoshi
• 金额: $ 5.38万
• 依托单位: Kumamoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044306/
• 关键词: calcium antagonist; photoaffinity labeling; cardiac calsium channel; drug binding site; new compounds; drug design; synthesic chemistry; 精密合成化学; 心筋L型Caチャンネル

In this project, we aim to reveal binding sites for calcium antagonists in cardiac calcium channels by photoaffinity laveling and the results are to be applied to design and synthesis of new drugs. New findings are as follows. (1) Benzothiazepine binding sites were identified in segment 5 and 6 in repeat IV by photoaffinity labeling using azidobutyryl clentiazem with a rather small-sized photoprobe. The recent report by foreign investigaters where two labeled sites in repeat III and IV must be a wrong conclusion resulted from using a bulky photoprobe with long side chain. (2) We revealed the binding site of semotiadil, a new typed calcium antagonist of 1,4-benzothiazine structure 1^^- which is homologous to benzothiazepine 2^^- but the identified sites were different. Theidentified site by photoaffinity labeling was solely in S6 of repeat IV which was partly shared with other calcium antagonist binding sites but not overlapped completely. The results can explain the pharmacological interactions among these drugs. (3) We also identified the semotiadil sites in cardiac channel, which were identical to the skeletal muscle counterpart but some amino acids were substituted. The substitution can be interpreted to dominate the difference of binding affinity and tissue selectivity in part in two calcium channels. (4) Three dimentional structures of 1 and 2 are not ovelapped by x-ray crystallographic analysis. It suggests that we will design and synthesis of improved calcium antagonists which are derived from 2 as a lead compound.

本课题旨在利用光亲和层析技术揭示钙拮抗剂在心肌钙通道中的结合位点，并将其应用于新药的设计和合成。新的调查结果如下。(1)苯并硫氮杂卓结合位点，确定在第5和第6段重复IV的光亲和标记使用叠氮丁酰克仑硫卓与一个相当小的光探针。最近国外研究者的报道认为，重复序列III和IV中的两个标记位点是一个错误的结论，这是由于使用了大体积的长侧链光探针。(2)我们揭示了一种新型的1，4-苯并噻嗪结构1^^-的钙拮抗剂semotiadil的结合位点，它与苯并硫氮杂卓2^^-具有同源性，但所鉴定的位点不同。光亲合标记的位点仅位于重复序列IV的S6，与其它钙拮抗剂结合位点部分共享，但不完全重叠。这些结果可以解释这些药物之间的药理相互作用。(3)我们还确定了心脏通道中的semotiadil位点，其与骨骼肌对应物相同，但一些氨基酸被取代。这种取代可以解释为在两个钙通道中部分地主导结合亲和力和组织选择性的差异。(4)X射线晶体学分析表明，化合物1和2的三维结构不对称。这表明，我们将设计和合成改进的钙拮抗剂，衍生自2作为先导化合物。

项目成果

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L.-C.Xu 等人：“基于羟酰胺的四齿配体作为一类新型无硫醇螯合分子的 ^<99m>Tc-放射性药物的合成和评估。”

Y.Hatanaka,et al.: "Diazirine-based photoaffinity labeling:Chemical approach to biological interfases." Rev.Heteroatom Chem.14. 213-243 (1996)

Y.Hatanaka 等人：“基于二氮丙啶的光亲和标记：生物界面的化学方法。”

A.Kuniyasu, et al.: "Photochemical identification of transmembrane segment IVS6 as the binding region of semotiadil, a new modulator for the voltage dependent Ca^<2+> channel." J.Biol.Chem.273. 4635-4641 (1998)

A.Kuniyasu 等人：“跨膜片段 IVS6 的光化学鉴定为 semotiadil 的结合区域，semotiadil 是电压依赖性 Ca^2 通道的新调节剂。”

A. M. Van Rhee, et al.: "Tetrahydrobenzothiophenone derivatives as a novel class of adenosine receptor antagonist" J. Med. Chem.39. 398-406 (1996)

A. M. Van Rhee 等人：“四氢苯并噻吩酮衍生物作为一类新型腺苷受体拮抗剂”J. Med。

S. Takeda, et al.: "Adenosine 5′-triphosphate binding to bovine serum albumin" Biophys. Chem.70. 175-183 (1997)

S. Takeda 等人：“腺苷 5-三磷酸与牛血清白蛋白的结合”Biophys.70（1997）。