Lambert William D, Scinto Samuel L, Dmitrenko Olga, Boyd Samantha J, Magboo Ronald, Mehl Ryan A, Chin Jason W, Fox Joseph M, Wallace Stephen
Brown Laboratory, Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Lotus Separations LLC, Newark, DE 19711, USA.
Org Biomol Chem. 2017 Aug 9;15(31):6640-6644. doi: 10.1039/c7ob01707c.
The use of organic chemistry principles and prediction techniques has enabled the development of new bioorthogonal reactions. As this "toolbox" expands to include new reaction manifolds and orthogonal reaction pairings, the continued development of existing reactions remains an important objective. This is particularly important in cellular imaging, where non-specific background fluorescence has been linked to the hydrophobicity of the bioorthogonal moiety. Here we report that trans-5-oxocene (oxoTCO) displays enhanced reactivity and hydrophilicity compared to trans-cyclooctene (TCO) in the tetrazine ligation reaction. Aided by ab initio calculations we show that the insertion of a single oxygen atom into the trans-cyclooctene (TCO) ring system is sufficient to impart aqueous solubility and also results in significant rate acceleration by increasing angle strain. We demonstrate the rapid and quantitative cycloaddition of oxoTCO using a water-soluble tetrazine derivative and a protein substrate containing a site-specific genetically encoded tetrazine moiety both in vitro and in vivo. We anticipate that oxoTCO will find use in studies where hydrophilicity and fast bioconjugation kinetics are paramount.
有机化学原理和预测技术的应用推动了新型生物正交反应的发展。随着这个“工具箱”不断扩展，纳入新的反应体系和正交反应配对，现有反应的持续改进仍然是一个重要目标。这在细胞成像中尤为重要，因为非特异性背景荧光与生物正交基团的疏水性有关。在此我们报告，在四嗪连接反应中，反式-5-氧代环辛烯（oxoTCO）相比于反式环辛烯（TCO）表现出更高的反应活性和亲水性。借助从头算计算，我们表明在反式环辛烯（TCO）环系统中插入单个氧原子足以赋予其水溶性，并且通过增加角张力还能显著加快反应速率。我们在体外和体内均展示了oxoTCO与水溶性四嗪衍生物以及含有位点特异性基因编码四嗪基团的蛋白质底物之间能快速定量地发生环加成反应。我们预计oxoTCO将在亲水性和快速生物共轭动力学至关重要的研究中得到应用。
