PDF(Pubmed)
Abstract：
Apamin is often cited as one of the few substances selectively acting on small-conductance Ca2+-activated potassium channels (KCa2). However, published pharmacological and structural data remain controversial. Here, we investigated the molecular pharmacology of apamin by two-electrode voltage-clamp in Xenopus laevis oocytes and patch-clamp in HEK293, COS7, and CHO cells expressing the studied ion channels, as well as in isolated rat brain neurons. The microtitre broth dilution method was used for antimicrobial activity screening. The spatial structure of apamin in aqueous solution was determined by NMR spectroscopy. We tested apamin against 42 ion channels (KCa, KV, NaV, nAChR, ASIC, and others) and confirmed its unique selectivity to KCa2 channels. No antimicrobial activity was detected for apamin against Gram-positive or Gram-negative bacteria. The NMR solution structure of apamin was deposited in the Protein Data Bank. The results presented here demonstrate that apamin is a selective nanomolar or even subnanomolar-affinity KCa2 inhibitor with no significant effects on other molecular targets. The spatial structure as well as ample functional data provided here support the use of apamin as a KCa2-selective pharmacological tool and as a template for drug design.
摘要：
Apamin通常被认为是选择性作用于小电导Ca2激活的钾通道（KCa2）的少数物质之一。然而,已发表的药理学和结构数据仍然存在争议。这里,我们通过双电极电压钳在非洲爪的卵母细胞中和膜片钳在表达所研究的离子通道的HEK293，COS7和CHO细胞中研究了阿帕明的分子药理学，以及孤立的大鼠脑神经元。微量滴定肉汤稀释法用于抗菌活性筛选。通过NMR光谱确定了水溶液中阿帕明的空间结构。我们测试了阿帕明对42个离子通道(KCa，KV,NaV,nAChR,ASIC,和其他)，并证实了其对KCa2通道的独特选择性。没有检测到阿帕明对革兰氏阳性或革兰氏阴性细菌的抗微生物活性。将阿帕明的NMR溶液结构保存在蛋白质数据库中。本文呈现的结果表明,阿帕明是选择性纳摩尔或甚至亚纳摩尔亲和力KCa2抑制剂,对其他分子靶标没有显著影响。本文提供的空间结构以及充足的功能数据支持使用阿帕明作为KCa2选择性药理学工具和作为药物设计的模板。
