Environmentally sensitive small molecule fluorescent probes for hERG potassium channels

Associate professor of shandong university professor min-yong li and Du Lvpei reported at the current activity of the best hERG potassium channel inhibitors astemizole for frame structure, the introduction of environmentally sensitive fluorophore in structure, the design for a class of novel hERG potassium channels small molecular fluorescent probe, horizontal selective markers used in living cells hERG potassium channels.  In the molecular structure of the probe, the environmentally sensitive fluorophore introduced as part of the designed recognition group can directly sense the hydrophobic interaction between the ligand molecule and the hERG potassium ion channel. This environment-sensitive fluorescent switch mechanism provides a new type of fluorescent switch design strategy for fluorescent probes targeting non-enzymatic protein targets.

Radioisotopic affinity tests showed that the probe had a high affinity with the HERG potassium ion channel, and the IC50 value reached nM level comparable to that of asmizole.At the same time, the results of cell voltage patch clamp showed that the probe had a high inhibitory activity on the potassium current of the HERG potassium ion channel with IC50 value of 41.65 nM.  The probe has good fluorescence properties. The fluorescence intensity increases with the increase of the hERG potassium ion channel concentration. When it reaches saturation, the fluorescence intensity increases by 6 times. In live cell imaging experiments, the probe can selectively label the hERG potassium ion channel, and due to the presence of the environment-sensitive fluorescent switch mechanism in the structure, there is no need to change the liquid during the entire imaging process, and the operation is simple.  In addition, the probe was aggregated in the lysosome of cells, which could reflect the distribution of asmizole in cells to some extent.