Kinetic study of the thermal denaturation of G actin using differential scanning calorimetry and intrinsic fluorescence spectroscopy.

Previous studies of the thermal denaturation of G actin have yielded conflicting results which have led to contradictory interpretations of the denaturation process. In their interpretations, these authors postulated that the thermal denaturation of G actin can be described by thermodynamical equilibrium laws despite the fact that this transition is irreversible. Using differential scanning calorimetry and fluorescence spectroscopy, we now show that thermal denaturation of G actin does not obey to equilibrium thermodynamics, but rather, is a two-step irreversible phenomenon under kinetic control. It can therefore be analyzed using the recently developed Sanchez-Ruiz equations.