Among the following, the maximum redox potential is for
Redox potentials of redox couples Cyt a3 Fe+2 = Cyt a3 Fe+3+0.386 REDOX POTENTIAL AND FREE ENERGY In the discussion so far, we have made it clear that an oxidising or reducing agent may exist in two forms, (a) the oxidised form or oxidant which can accept electrons and (b) the reductant which can donate its electrons to a substrate. Each oxidizing or reducing agent exists as a conjugate pair of electron acceptor oxidant and electron donor reductant forms. Where 'n' is the number of electrons. The pair consisting of the oxidant and reductant forms of an oxidizing or reducing agent is known as a redox couple or conjugate redox pair, e.g. NAD+/NADH, FMN/FMNH2, Cyt-c Fe++/Cyt-c Fe+++. Oxidising agents differ in their electron affinity. The standard redox potential Eo is a measure of the tendency of a redox couple to donate or accept electrons under standard conditions. The redox potential of a given system is intimately related to its free energy change. If redox-potential of a given system is known, the corresponding free energy change which might occur in the system on oxidation or reduction may be found as follows: DF= -nfDE'o Coulomb Joules Where F= Standard free energy n= no. of electrons f = Faraday's constant (96,500 Coulombs) DE'o = Difference between redox potentials of the couple. nfDE'o orDF = ____________ calories 4.18 If the sign of free-energy thus calculated is negative, it indicates free energy release and if positive, it indicates free energy consumptionRef: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 138
NADH/NAD
Succinyl Co A fumarate
Ubiquinone
Fe 2+
Respiratory chain