Observation of the controlled assembly of preclick components in the in situ click chemistry generation of a chitinase inhibitor
Observation of the controlled assembly of preclick components in the in situ click chemistry generation of a chitinase inhibitor
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DOI：
10.1073/pnas.1315049110
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发表时间：
2013-10-01
影响因子：
11.1
通讯作者：
Sunazuka, Toshiaki
中科院分区：
文献类型：
--
作者：
Hirose, Tomoyasu;Maita, Nobuo;Sunazuka, Toshiaki
在目标生物分子的促进下，叠氮化物和炔烃的惠氏环加成反应被称为“原位点击化学”，已经成功地被用来发现高效的酶抑制剂。我们之前已经报道了一种特异性的粘质沙雷氏菌几丁质酶B(SmChiB)模板联三唑抑制剂，它是由叠氮类抑制剂和炔基片段原位生成的。已经报道了几个原位点击化学研究。尽管已经获得了一些机制证据，例如对[蛋白质]-[“点击配体”]络合物的X射线分析，表明蛋白质在独特的叠氮化物和炔片段对之间既是模子又是模板，但到目前为止，观察结果仅基于“点击后”的结构信息。在这里，我们描述了SmChiB与叠氮配体和O-烯丙基肟片段络合的晶体结构，作为对点击伙伴的模拟，揭示了一种加速合成三氮唑的机制，这使得它可以产生自己独特的抑制剂。我们还基于X射线结构进行了密度泛函理论计算，探讨了SmChiB对惠氏环加成反应的加速作用。密度泛函理论计算合理地支持了SmChiB在选择性并三氮唑点击形成的翻译前和翻译后状态中通过笼形效应起作用。
The Huisgen cycloaddition of azides and alkynes, accelerated by target biomolecules, termed "in situ click chemistry,"has been successfully exploited to discover highly potent enzyme inhibitors. We have previously reported a specific Serratia marcescens chitinase B (SmChiB)-templated syn-triazole inhibitor generated in situ from an azide-bearing inhibitor and an alkyne fragment. Several in situ click chemistry studies have been reported. Although some mechanistic evidence has been obtained, such as X-ray analysis of [ protein]-["click ligand"] complexes, indicating that proteins act as both mold and template between unique pairs of azide and alkyne fragments, to date, observations have been based solely on "postclick" structural information. Here, we describe crystal structures of SmChiB complexed with an azide ligand and an O-allyl oxime fragment as a mimic of a click partner, revealing a mechanism for accelerating syn-triazole formation, which allows generation of its own distinct inhibitor. We have also performed density functional theory calculations based on the X-ray structure to explore the acceleration of the Huisgen cycloaddition by SmChiB. The density functional theory calculations reasonably support that SmChiB plays a role by the cage effect during the pretranslation and posttranslation states of selective syn-triazole click formation.