Question

1. A protein is said to be denatured when it loses some of its unique characteristics because its structure is changed.  The enthalpy change for the denaturation of a certain protein is 142 kJ/mol, while its entropy change is 278 J/K.  What is the minimum temperature at which the protein would denature spontaneously?

Answer 1

As the temperature increases, protein will become less viscous. At this point the protein molecules may obtain enough freedom of motion to spontaneously arrange themselves into a crystalline form and as a results, a peak appeared in the DSC signal (First peak- Denaturaion temperature). In this state the protein chains can refold themselves. As the temperature increases further, the protein eventually reaches its melting temperature (Tm) (a second point on the stability curve where free energy change ΔG is equal to zero). At this point the protein molecules disappear into amorphous state and the protein chains cannot refold themselves.