Department of Biomolecular Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
Chembiochem. 2018 Aug 6;19(15):1648-1652. doi: 10.1002/cbic.201800275. Epub 2018 Jun 28.
Bioorthogonal chemistry can be used for the selective modification of biomolecules without interfering with any other functionality that might be present. Recent developments in the field include orthogonal bioorthogonal reactions to modify multiple biomolecules simultaneously. During our research, we observed that the reaction rates for the bioorthogonal inverse-electron-demand Diels-Alder (iEDDA) reactions between nonstrained vinylboronic acids (VBAs) and dipyridyl-s-tetrazines were exceptionally higher than those between VBAs and tetrazines bearing a methyl or phenyl substituent. As VBAs are mild Lewis acids, we hypothesised that coordination of the pyridyl nitrogen atom to the boronic acid promoted tetrazine ligation. Herein, we explore the molecular basis and scope of VBA-tetrazine ligation in more detail and benefit from its unique reactivity in the simultaneous orthogonal tetrazine labelling of two proteins modified with VBA and norbornene, a widely used strained alkene. We further show that the two orthogonal iEDDA reactions can be performed in living cells by labelling the proteasome by using a nonselective probe equipped with a VBA and a subunit-selective VBA bearing a norbornene moiety.
生物正交化学可用于选择性修饰生物分子，而不会干扰可能存在的任何其他功能。该领域的最新进展包括正交生物正交反应，可同时修饰多种生物分子。在我们的研究中，我们观察到非张力乙烯基硼酸（VBAs）和二吡啶-s-四嗪之间的生物正交逆电子需求 Diels-Alder（iEDDA）反应的反应速率明显高于 VBAs 和带有甲基或苯基取代基的四嗪之间的反应速率。由于 VBAs 是温和的路易斯酸，我们假设吡啶氮原子与硼酸的配位促进了四嗪的连接。在此，我们更详细地探讨了 VBA-四嗪连接的分子基础和范围，并受益于其在同时对用 VBAs 和广泛使用的张力烯烃降冰片烯修饰的两种蛋白质进行正交四嗪标记方面的独特反应性。我们进一步表明，通过使用带有 VBAs 的非选择性探针和带有降冰片烯部分的亚基选择性 VBA，可以在活细胞中进行两种正交 iEDDA 反应，从而对蛋白酶体进行标记。
