Coordination to Imidazole Ring Switches on Phosphorescence of Platinum Cyclometalated Complexes: The Route to Selective Labeling of Peptides and Proteins via Histidine Residues

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• 作者：Anastasia I. Solomatina ; Pavel S. ChelushkinDmitrii V. Krupenya ; Ivan S. PodkorytovTatiana O. Artamonova ; Vladimir V. Sizov ; Alexei S. Melnikov ; Vladislav V. Gurzhiy ; Elena I. Koshel ; Vladislav I. Shcheslavskiy ; Sergey P. Tunik
• 刊名：Bioconjugate Chemistry
• 出版年：2017
• 出版时间：February 15, 2017
• 年：2017
• 卷：28
• 期：2
• 页码：426-437
• 全文大小：636K
• ISSN：1520-4812

文摘

In this study, we have shown that substitution of chloride ligand for imidazole (Im) ring in the cyclometalated platinum complex Pt(phpy)(PPh₃)Cl (1; phpy, 2-phenylpyridine; PPh₃, triphenylphosphine), which is nonemissive in solution, switches on phosphorescence of the resulting compound. Crystallographic and nuclear magnetic resonance (NMR) spectroscopic studies of the substitution product showed that the luminescence ignition is a result of Im coordination to give the [Pt(phpy)(Im)(PPh₃)]Cl complex. The other imidazole-containing biomolecules, such as histidine and histidine-containing peptides and proteins, also trigger luminescence of the substitution products. The complex 1 proved to be highly selective toward the imidazole ring coordination that allows site-specific labeling of peptides and proteins with 1 using the route, which is orthogonal to the common bioconjugation schemes via lysine, aspartic and glutamic acids, or cysteine and does not require any preliminary modification of a biomolecule. The utility of this approach was demonstrated on (i) site-specific modification of the ubiquitin, a small protein that contains only one His residue in its sequence, and (ii) preparation of nonaggregated HSA-based Pt phosphorescent probe. The latter particles easily internalize into the live HeLa cells and display a high potential for live-cell phosphorescence lifetime imaging (PLIM) as well as for advanced correlation PLIM and FLIM experiments.