A thermodynamic analysis of two-state transitions under high pressure: Theoretical considerations

Possible effects of high pressure on heat denaturation of biopolymers have been analyzed. The study was made using an equilibrium model of transition between two states. Equations used to determine the dependence of thermodynamic parameters of transition (enthalpy, entropy and transition temperature) on pressure were formulated. Pressure may have both stabilizing and destabilizing effects on the macromolecule structure depending on the change in the volume upon transition. The dependence of the transition temperature on pressure cannot have local extremums. It is demonstrated that depending on the increment (jump) of the partial expansion coefficient and the change of the transition temperature, the enthalpy of transition can both grow with the pressure growth or decrease. It is also .shown that when the pressure grows, the changes in the volume and enthalpy under denaturation cannot change their signs.