I've followed many articles to find out the relationship of various concentrations and the potential of GSH or GSSG in different cellular organelles but it's quite confusing for me to find out how do we convert these to different entities to each other?
Can someone please explain the Nernst equation to find out the potential of different cellular compartments?
The use of GSH and GSSG concentrations to calculate redox potentials using the Nernst equation has been criticized for several reasons. Take a look at these two references:
Article The fairytale of the GSSG/GSH redox potential
Article Redox regulation by glutathione needs enzymes
The Nerst equation might tell you up to which point the ions will be crossing the membrane, depending on their status on the membrane barrier. We normslly say K but then the rest of the ions, (up to 3). Maybe you mean the Goldmann equation.? K+ normally means 1. Na+ and Cl-. Cl- is always negative and is always to be expected to be on the side of the membrane. This means it might be still (0) as all the ions will pass.
I think this article will be helpful for you.....Please go through this link below...
Article Glutathione-dependent reductive stress triggers mitochondria...
Since Glutathione is redox active molecule, you may consider using Boltzmann factor. In this case, the ratio of oxidise to reduce glutahione molecule will be [GSH/GSSG] which is equivalent to the probability of glutathione being oxidized (giving electrons) over the probability of being reduced (taking electrons) which we can write in terms of the Boltzmann factor for these processes.
[GSH]/[GSSG] = exp(-[barriers for gaining electron]/kT)/exp(-[barriers for losing electron]/kT)
=exp(μc/kT)------------Eqn.1
where μc= the chemical potential of the glutathione solution and is the difference between the energy barriers for taking electrons from and for giving electrons to the working electrode that is setting the solution's electrochemical potential.
Taking the natural logarithm of both sides from Eqn.1 gives
μc=kT In [GSH]/[GSSG] -------Eqn.2
If μc ≠ 0 at [GSH]/[GSSG] = 1, we need to add in this additional constant
μc=μc0 + kT In [GSH]/[GSSG]-----Eqn.3
where μc0= standard chemical potential of glutathione
Dividing the equation by e to convert from chemical potentials to electrode potentials, and remembering that k/e = R/F, we obtain the Nernst equation for the one-electron process GSSG + e− → GSH:
then
E=E0 - kT/e In [GSH/GSSG] --------Eqn.4
E=E0 - RT/F In [GSH/GSSG]---------Eqn.5
A convenient expression for the redox state of the GSH/GSSG pool that incorporates the correct stoichiometry of 2 GSH oxidized per GSSG formed is the redox potential (Eh), calculated according to the Nernst equation:
Eh = Eo + (RT/nF)ln([acceptor]/[donor])
see this article for more information Article Redox potential of GSH/GSSG couple: Assay and biological significance
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