Figure 7

The reversibility of the thermal denaturation of WT and mutant DENV2C proteins were evaluated by circular dichroism. CD spectra were obtained in a Chirascan (Applied Photophysics, United Kingdom) using quartz cuvettes with 0.1-cm path lengths. The proteins were diluted in 50 mM sodium phosphate buffer (pH 6.0)/200 mM NaCl to a final concentration of 10 µM. Spectra were collected every 2 °C from 20 to 90 °C, with one acquisition at each temperature and to evaluate the reversibility of denaturation, spectra were also collected every 2 °C from 90 to 20 °C. The molar ellipticity at 222 nm was used to evaluate the changes in the secondary structure of these proteins promoted by the temperature. The CD signal at 222 nm was converted into a folded fraction (α) value and plotted against temperature. The folded fraction curves acquired from 20 to 90 °C and from 90 to 20 °C were superimposed and are shown in (A–E).