英国曼彻斯特大学Green, Anthony P.团队报道了对映选择性[2+2]环加成物的光酶设计。相关研究成果发表在2022年9月21日出版的国际知名学术期刊《自然》。
将新的催化模式编辑到蛋白质中的能力将能够开发具有超出自然界功能的酶家族。为此，遗传密码扩展方法具有特别的前景，因为它能够将新的功能元素作为非标准氨基酸侧链选择性地引入蛋白质。
该文中，研究人员利用扩展的遗传密码来开发一种通过三重态能量转移催化进行操作的光酶，这是目前生物催化无法实现的有机合成中的一种多功能反应模式。将基因编码光敏剂安装到DA_20_0013的β螺旋桨支架中，可将从头Diels Alderase转化为[2+2]-环加成的光酶（EnT1.0）。光酶进化平台的后续开发和实施提供了一种高效的对映体选择性酶（EnT1.3，最高99%e.e.），可以促进分子内和双分子环加成，包括已证明难以用小分子催化剂选择性实现的转化。EnT1.3的转化率大于300，与小分子光催化剂相比，它可以在有氧条件和环境温度下有效运行。EnT1.3产品复合物的X射线晶体结构显示了多个功能组分如何协同工作，以促进高效和选择性光催化。
该项研究在蛋白质活性中心开辟了大量新的激发态化学，并为开发新一代对映体选择性光催化剂建立了框架。
附：英文原文
Title: A Designed Photoenzyme for Enantioselective [2+2]-Cycloadditions
Author: Trimble, Jonathan S., Crawshaw, Rebecca, Hardy, Florence J., Levy, Colin W., Brown, Murray J. B., Fuerst, Douglas E., Heyes, Derren J., Obexer, Richard, Green, Anthony P.
Issue&Volume: 2022-09-21
Abstract: The ability to programme 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 non-canonical amino acid side chains.1-4 Here, we exploit an expanded genetic code to develop a photoenzyme that operates via triplet energy transfer catalysis, a versatile mode of reactivity in organic synthesis that is currently not accessible to biocatalysis.5-12 Installation of a genetically encoded photosensitiser into the beta-propeller scaffold of DA_20_0013 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% e.e.) that can promote intramolecular and bimolecular cycloadditions, including transformations that have proven 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.
DOI: 10.1038/s41586-022-05335-3
Source: https://www.nature.com/articles/s41586-022-05335-3