Tu Julian, Svatunek Dennis, Parvez Saba, Eckvahl Hannah J, Xu Minghao, Peterson Randall T, Houk K N, Franzini Raphael M
Department of Medicinal Chemistry , College of Pharmacy , University of Utah , Salt Lake City , 84112 , USA . Email:
Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , USA.
Chem Sci. 2019 Nov 5;11(1):169-179. doi: 10.1039/c9sc04649f. eCollection 2020 Jan 7.
compatible reactions have a broad range of possible applications in chemical biology and the pharmaceutical sciences. Here we report tetrazines that can be removed by exposure to isonitriles under very mild conditions. Tetrazylmethyl derivatives are easily accessible protecting groups for amines and phenols. The isonitrile-induced removal is rapid and near-quantitative. Intriguingly, the deprotection is especially effective with (trimethylsilyl)methyl isocyanide, and serum albumin can catalyze the elimination under physiological conditions. NMR and computational studies revealed that an imine-tautomerization step is often rate limiting, and the unexpected cleavage of the Si-C bond accelerates this step in the case with (trimethylsilyl)methyl isocyanide. Tetrazylmethyl-removal is compatible with use on biomacromolecules, in cellular environments, and in living organisms as demonstrated by cytotoxicity experiments and fluorophore-release studies on proteins and in zebrafish embryos. By combining tetrazylmethyl derivatives with previously reported tetrazine-responsive 3-isocyanopropyl groups, it was possible to liberate two fluorophores in vertebrates from a single bioorthogonal reaction. This chemistry will open new opportunities towards applications involving multiplexed release schemes and is a valuable asset to the growing toolbox of bioorthogonal dissociative reactions.
相容性反应在化学生物学和药物科学领域有着广泛的潜在应用。在此，我们报道了一类四嗪化合物，它们在非常温和的条件下通过与异腈接触即可被去除。四嗪甲基衍生物是用于胺类和酚类的易于获得的保护基团。异腈诱导的去除反应迅速且接近定量。有趣的是，脱保护反应在（三甲基硅基）甲基异腈存在下特别有效，并且血清白蛋白可在生理条件下催化消除反应。核磁共振（NMR）和计算研究表明，亚胺互变异构步骤通常是限速步骤，而在（三甲基硅基）甲基异腈存在的情况下，意外的硅 - 碳键断裂加速了这一步骤。如在蛋白质和斑马鱼胚胎上进行的细胞毒性实验和荧光团释放研究所表明的，四嗪甲基的去除与在生物大分子、细胞环境和活生物体中的应用是相容的。通过将四嗪甲基衍生物与先前报道的对四嗪有响应的3 - 异氰基丙基基团相结合，有可能通过单一的生物正交反应在脊椎动物中释放两种荧光团。这种化学方法将为涉及多重释放方案的应用带来新的机遇，并且是不断发展的生物正交解离反应工具箱中的一项宝贵资产。
