α-selenoconotoxins, a new class of potent α7 neuronal nicotinic receptor antagonists
α-selenoconotoxins, a new class of potent α7 neuronal nicotinic receptor antagonists
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DOI：
10.1074/jbc.m512419200
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发表时间：
2006-05-19
影响因子：
4.8
通讯作者：
Alewood, Paul F.
中科院分区：
文献类型：
--
作者：
Armishaw, Christopher J.;Daly, Norelle L.;Alewood, Paul F.
二硫键是重要的结构基序，在维持许多生物活性肽的构象稳定性方面起着至关重要的作用。芋螺毒素尤为重要，它能选择性地靶向多种与众多疾病状态相关的离子通道。尽管芋螺毒素作为治疗药物具有巨大潜力，但它们的多个二硫键框架在还原条件下本身不稳定。在细胞内或细胞外环境（如血浆）中，含巯基的分子（如谷胱甘肽或血清白蛋白）对其进行还原或错配会降低它们作为药物的有效性。为了解决这个问题，我们描述了一类新的硒代芋螺毒素，其中半胱氨酸残基被硒代半胱氨酸取代，形成等排且不可还原的二硒键。通过叔丁氧羰基化学方法合成了α -芋螺毒素ImI的三种异构体，系统地将一个（[Sec(2,8)] ImI或[Sec(3,12)] ImI）或两个（[Sec(2,3,8,12)] ImI）二硫键替换为二硒键。每种类似物在一系列化学和生物还原条件下都表现出对还原或错配的显著稳定性。通过核磁共振和圆二色谱进行的三维结构表征表明，其构象偏好与天然ImI非常相似，这表明它们具有完全同构的结构。此外，在α(7)烟碱型乙酰胆碱受体上保留了完全的生物活性，每种硒代类似物的剂量 - 反应曲线都与野生型ImI重叠，从而进一步支持了同构结构。这些结果表明，硒代芋螺毒素可作为高度稳定的支架用于新药设计。
Disulfide bonds are important structural motifs that play an essential role in maintaining the conformational stability of many bioactive peptides. Of particular importance are the conotoxins, which selectively target a wide range of ion channels that are implicated in numerous disease states. Despite the enormous potential of conotoxins as therapeutics, their multiple disulfide bond frameworks are inherently unstable under reducing conditions. Reduction or scrambling by thiol-containing molecules such as glutathione or serum albumin in intracellular or extracellular environments such as blood plasma can decrease their effectiveness as drugs. To address this issue, we describe a new class of selenoconotoxins where cysteine residues are replaced by selenocysteine to form isosteric and non-reducible diselenide bonds. Three isoforms of alpha-conotoxin ImI were synthesized by t-butoxycarbonyl chemistry with systematic replacement of one([ Sec(2,8)] ImI or [Sec(3,12)] ImI), or both([Sec(2,3,8,12)] ImI) disulfide bonds with a diselenide bond. Each analogue demonstrated remarkable stability to reduction or scrambling under a range of chemical and biological reducing conditions. Three-dimensional structural characterization by NMR and CD spectroscopy indicates conformational preferences that are very similar to those of native ImI, suggesting fully isomorphic structures. Additionally, full bioactivity was retained at the alpha(7) nicotinic acetylcholine receptor, with each seleno-analogue exhibiting a dose-response curve that overlaps with wild-type ImI, thus further supporting an isomorphic structure. These results demonstrate that selenoconotoxins can be used as highly stable scaffolds for the design of new drugs.