Circular dichroism spectroscopy of Sp-DHDPS.
(A) CD spectrum of Sp-DHDPS () plotted as the molar circular dichroism (Δε) as a function of wavelength. The solid line represents the nonlinear least squares fit using the CONTINLL algorithm and SP43 database within the CDPRO software suite [48.49]. The best-fit resulted in the secondary structure composition reported in Table 3. (B) Thermal denaturation profiles of Sp-DHDPS () and Ec-DHDPS () plotted as mean residue ellipticity (MRE) versus temperature. The apparent melting temperature (TMapp), or midpoint of the transition between folded and unfolded states, was determined from the ordinate maximum of a plot of the first derivative of the MRE as a function of temperature to yield 59°C for Ec-DHDPS and 72°C for Sp-DHDPS.