Exact Solution to the Extended Zwanzig Model for Quasi-Sigmoidal Chemically Induced Denaturation Profiles: Specific Heat and Configurational Entropy

Figure 3

Specific heat 𝐶_𝑣 for a poly-alanine (poly-A) and poly-valine (poly-V) chains under a slow-fast denaturation mode (type A) and a fast-slow denaturation mode (type B). In both cases, the number of residues was set to 𝐾=40, 𝑈=0.75×10³ J mol⁻¹, 𝜖=35×10³ J mol⁻¹. Type A mechanism is characterized by 𝐴₁=0.32, 𝐴₂=16.19, 𝐴₃=6.25, 𝐾₁=39, and 𝐾₂=5 whereas type B is defined through parameters 𝐴₁=64, 𝐴₂=0.44, 𝐴₃=6, 𝐾₁=8, and 𝐾₂=6. Helical propensity 𝜔_𝐴=1.61 was considered for alanine while 𝜔_𝑉=0.23 was considered for valine.

(a)

(b)