Design of Spiro[2.3]hex-1-ene, a Genetically Encodable Double-Strained Alkene for Superfast Photoclick Chemistry

Reactive yet stable alkene reporters
offer a facile route to studying
fast biological processes via the cycloaddition-based bioorthogonal
reactions. Here, we report the design and synthesis of a strained
spirocyclic alkene, spiro[2.3]­hex-1-ene (Sph), for an accelerated
photoclick chemistry, and its site-specific introduction into proteins
via amber codon suppression using the wild-type pyrrolysyl-tRNA synthetase/tRNACUA pair. Because of its high ring strain and reduced steric
hindrance, Sph exhibited fast reaction kinetics (k2 up to 34 000 M–1 s–1) in the photoclick chemistry and afforded rapid (<10 s) bioorthogonal
protein labeling.

兼具反应活性与稳定性的烯烃报告试剂，为通过基于环加成（cycloaddition）的生物正交反应（bioorthogonal reactions）研究快速生物学过程提供了便捷途径。本研究报道了一种用于加速型光点击化学反应（photoclick chemistry）的张力型螺环烯烃——螺[2.3]己-1-烯（spiro[2.3]hex-1-ene，简称Sph）的设计与合成，并借助野生型吡咯赖氨酰-tRNA合成酶（pyrrolysyl-tRNA synthetase）/tRNACUA对，通过琥珀密码子抑制（amber codon suppression）技术实现其在蛋白质中的位点特异性引入。由于具备较高的环张力与较低的空间位阻，Sph在光点击化学反应中展现出快速的反应动力学性能（二级速率常数k2最高可达34000 M–1 s–1），可实现耗时不足10秒的生物正交蛋白质标记。