A designed photoenzyme for enantioselective [2+2] cycloadditions
A designed photoenzyme for enantioselective [2+2] cycloadditions
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DOI：
10.1038/s41586-022-05335-3
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发表时间：
2022-09-21
期刊：
影响因子：
64.8
通讯作者：
Green, Anthony P.
中科院分区：
文献类型：
--
作者：
Trimble, Jonathan S.;Crawshaw, Rebecca;Green, Anthony P.
将新的催化模式编程到蛋白质中的能力将允许开发具有超出自然界中发现的功能的酶家族。为此，遗传密码扩展方法具有特别的前景，因为它允许将新的功能元件作为非经典氨基酸侧链位点选择性地引入蛋白质中（1-4）。在这里，我们利用扩展的遗传密码来开发一种通过三重态能量转移（EnT）催化作用进行操作的光酶，这是一种目前生物催化无法实现的有机合成反应的通用模式（5-）（12）。将遗传编码的光敏剂安装到DA_20_00的β-螺旋桨支架中（参考文献(13))将从头第尔斯-阿尔德酶转化为[2+2]环加成的光酶（EnT1.0）。随后开发和实施的一个平台的光酶进化提供了一个有效的和对映体选择性的酶（EnT1.3，高达99%的对映体过量（e.e.））这可以促进分子内和双分子环加成，包括已被证明具有挑战性的转化，以实现选择性的小分子催化剂。EnT1.3的周转次数超过300次，与小分子光催化剂相比，它可以在有氧条件下和环境温度下有效运行。EnT1.3-产物复合物的X射线晶体结构显示了多个功能组分如何协同工作以促进有效和选择性的降解。该研究为蛋白质活性中心的激发态化学研究开辟了新的途径，为开发新一代的对映选择性光催化剂奠定了基础。
The ability to program new modes of catalysis into proteins would allow the development of enzyme families with functions beyond those found in nature. To this end, genetic code expansion methodology holds particular promise, as it allows the site-selective introduction of new functional elements into proteins as noncanonical amino acid side chains(1-4). Here we exploit an expanded genetic code to develop a photoenzyme that operates by means oftriplet energy transfer (EnT) catalysis, a versatile mode of reactivity in organic synthesis that is not accessible to biocatalysis at present(5-)(12). Installation of a genetically encoded photosensitizer into the beta-propeller scaffold of DA_20_00 (ref.(13)) converts a de novo Diels-Alderase into a photoenzyme for [2+2] cycloadditions (EnT1.0). Subsequent development and implementation of a platform for photoenzyme evolution afforded an efficient and enantioselective enzyme (EnT1.3, up to 99% enantiomeric excess (e.e.)) that can promote intramolecular and bimolecular cycloadditions, including transformations that have proved challenging to achieve selectively with small-molecule catalysts. EnT1.3 performs >300 turnovers and, in contrast to small-molecule photocatalysts, can operate effectively under aerobic conditions and at ambient temperatures. An X-ray crystal structure of an EnT1.3-product complex shows how multiple functional components work in synergy to promote efficient and selective photocatalysis. This study opens up a wealth of new excited-state chemistry in protein active sites and establishes the framework for developing a new generation of enantioselective photocatalysts.