Fig. 6.
Thermal Shift Assay (TSA) of SARS-CoV-2 3CLpro stability and interaction with Epigallocatechin-3-gallate (EGCG). A. The experimental system for TSA was validated using quercetin, a compound that was previously reported to alter the thermal stability of 3CLpro by causing destabilization. The melting temperatures (Tm) was identified by plotting the first derivative of the fluorescence emission as a function of temperature (−dF/dT). Tm is represented as the lowest part of the curve. B. The melting temperature (Tm) of 3CLpro with various concentrations of EGCG, showing a dose-dependent trend. C and D. The sigmoidal curves showing the melting temperatures (Tm) of dimethyl sulfoxide (C; negative control) and 62.5 μM EGCG (D). The solid line represents the non-linear fit of the fluorescence curve to Boltzmann Equation.