Figure 1.

The principle of the developed FP screening assay for discovery of Mpro inhibitors

In this FP assay, incubation of FP probes (dashed purple line) with active Mpro (the scissors) and subsequent addition of avidin (red crescent) will produce a FP signal that is proportional to the relative amount of cleaved and uncleaved FP probes. In the presence of a bioactive compound (blue hexagon) that inhibits Mpro activity, the uncleaved FP probe produces a high mP value upon binding to avidin, whereas in the presence of an inactive compound (yellow hexagon), the cleaved fragment FITC-AVLQ produces a low mP value because of the failure for avidin binding. This adapted graphic is produced with permission (Yan et al., 2022b).