Fig. 2.

Spectroscopic thermal unfolding of SARS-CoV-2 3CLpro. (a) Far-UV CD thermal unfolding monitoring the (raw) ellipticity at 222 nm, at 10 μM protein concentration. (b) Fluorescence thermal unfolding monitoring the intrinsic tryptophan fluorescence emission at 330 nm, at 2 μM protein concentration. Both experiments were recorded at pH 8. The experimental data (circles) and the non-linear regression analysis fitting curves (continuous lines) according to two-state monomeric, dimeric and tetrameric protein are shown (indistinguishable in the plot).