State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, 210093, Nanjing, China.
Nat Commun. 2019 Jan 11;10(1):142. doi: 10.1038/s41467-018-08010-2.
Efficient and site-specific chemical modification of proteins under physiological conditions remains a challenge. Here we report that 1,4-dinitroimidazoles are highly efficient bifunctional bioconjugation reagents for protein functionalization and peptide macrocyclization. Under acidic to neutral aqueous conditions, 1,4-dinitroimidazoles react specifically with cysteines via a cine-substitution mechanism, providing rapid, stable and chemoselective protein bioconjugation. On the other hand, although unreactive towards amine groups under neutral aqueous conditions, 1,4-dinitroimidazoles react with lysines in organic solvents in the presence of base through a ring-opening & ring-close mechanism. The resulting cysteine- and lysine-(4-nitroimidazole) linkages exhibit stability superior to that of commonly employed maleimide-thiol conjugates. We demonstrate that 1,4-dinitroimidazoles can be applied in site-specific protein bioconjugation with functionalities such as fluorophores and bioactive peptides. Furthermore, a bisfunctional 1,4-dinitroimidazole derivative provides facile access to peptide macrocycles by crosslinking a pair of cysteine or lysine residues, including bicyclic peptides of complex architectures through highly controlled consecutive peptide macrocyclization.
在生理条件下高效且定点的蛋白质化学修饰仍然是一项挑战。在这里，我们报告 1,4-二硝基咪唑是用于蛋白质功能化和肽大环化的高效双功能生物偶联试剂。在酸性至中性水条件下，1,4-二硝基咪唑通过亲核取代机制特异性地与半胱氨酸反应，提供快速、稳定和化学选择性的蛋白质生物偶联。另一方面，尽管在中性水条件下对胺基无反应，但在碱存在下，1,4-二硝基咪唑在有机溶剂中通过开环和闭环机制与赖氨酸反应。所得的半胱氨酸和赖氨酸-(4-硝基咪唑)键合具有优于常用马来酰亚胺-巯基缀合物的稳定性。我们证明了 1,4-二硝基咪唑可用于带有荧光团和生物活性肽等官能团的定点蛋白质生物偶联。此外，双功能 1,4-二硝基咪唑衍生物通过交联一对半胱氨酸或赖氨酸残基提供了制备肽大环的简便方法，包括通过高度控制的连续肽大环化形成复杂结构的双环肽。
