Free energy and irreversible processes

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SUMMARY

The discussion centers on the calculation of Gibbs free energy for irreversible processes, specifically in the context of protein thermal stability. The conventional method of determining Gibbs free energy difference (ΔG) relies on the equilibrium constant (K) for reversible reactions, expressed as ΔG = -RT ln K. However, the user faces challenges due to the irreversible unfolding of the protein (N → U). They explore alternative approaches, including kinetics and the Arrhenius activation energy, and propose a formula for ΔG involving changes in enthalpy and entropy.

PREREQUISITES
  • Understanding of Gibbs free energy and its relation to equilibrium constants
  • Knowledge of protein folding and unfolding mechanisms
  • Familiarity with Arrhenius equation and activation energy concepts
  • Basic principles of thermodynamics, particularly enthalpy and entropy
NEXT STEPS
  • Research the calculation of Gibbs free energy for irreversible processes
  • Explore advanced kinetics and their application to protein stability
  • Study the relationship between enthalpy, entropy, and free energy in thermodynamics
  • Investigate alternative methods for assessing protein stability beyond Gibbs free energy
USEFUL FOR

Biochemists, molecular biologists, and researchers focused on protein stability and thermodynamics, particularly those dealing with irreversible processes in protein folding.

arwelbath
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Hi,
I'm working on a problem of the thermal stability of a protein. Conventionlly, people compare protein thermal stability in terms of the Gibbs free energy difference between the native and unfolded state. So if it reversibly falls apart, then for N <==> U, DG(N-U) is accessed from the classical equilibrium constant for the process. (DG = -RT ln K)

But, unfortunately my system unfolds irreversibly so that N --> U.

Is the gibbs free energy defined for an irreversible process? If so, how can it be calculated without an equilibrium constant? If it's not defined, is there an equilvalent quantity which can be used?

The best I can do so far is to look at the kinetics, which I've done and got an Arrhenius activation energy. Can I get any more information from this?

Please Help!
 
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I'm pretty sure you can find delta G by using the equation
delta G = (delta H) - delta(TS) --> delta G = (Cp * delta T) - (TfSf - TiSi)

Hope this helps
 

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