Fig. 4.

Temperature and pressure dependence of the amide-I band of the AK peptide. (a) The simulated amide-I band at four values of pressure and temperature (low T, low-P; low T, high P; high T, low P; and high T, high P). The dark and gray lines show pressure dependence at low (300 K) and high (547 K) temperatures. The solid and dashed lines correspond to low (ρ = 1.0 g·cm^–3) and high (ρ = 1.14 g·cm^–3) densities. (b and c) Plots correspond to the contribution from the internal (helical) (b) and external (solvent) (c) hydrogen bonding to the amide-I frequency. These contributions will lower the amide-I frequency of the individual carbonyls by the frequency shift given in cm^–1.