Fig. 2: Temperature-dependent far-UV SRCD spectra of [C − Mb][S] in different solvents.

a ChCl:Glyc, (b) TBAC:Glyc, (c) TBAC:OA, and (d) aqueous buffer, showing progressive thermal denaturation between 0 °C (blue) and 200 °C (red) in DESs and between 20 °C (blue) and 90 °C (red) in aqueous buffer. All data were recorded in 5 °C steps. e Plots of fraction denatured against temperature and (f) Gibbs free energy of denaturation as a function of temperature over the linear transition region of [C−Mb][S] in DESs. These parameters were calculated from SRCD data for [C-Mb][S] in ChCl:Glyc (red triangles), TBAC:Glyc (blue circles), TBAC:OA (green diamonds), and water (black squares). Data in were fitted to the models (dotted lines) to determine the thermodynamics of protein denaturation as described in the Supplementary Methods.