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Standard Reduction Potential of Any Redox Pair

Standard Reduction Potentials: The standard reduction potential, E10, of any redox pair is defined for the half-cell reaction:

Oxidizing agent + n electrons -----> reducing agent

The E10 value for the NAD+/ NADH and pyruvate/lactate conjugate redox pairs are -0.32 V and -0.19 V, respectively.
(a) Which conjugate pair has the greater tendency to lose electrons? Explain.
(b) Which is the stronger oxidizing agent? Explain
(c) Beginning with 1m concentration of each reactant and product at pH 7, in which direction will the following reaction proceed?
Pyruvate + NADH +H+ ------> lactate + NAD+
(d) What is the standard free-energy change (∆G10) at 25 degrees C for the conversion of pyruvate to lactate?
(e) What is the equilibrium constant (K'eq) for this reaction?

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a) NAD+/NADH has greater tendency to lose electrons because they are water soluble cofactors. So these cofactors readily diffuse from the surface of one enzyme to another, acting as a water soluble carrier of electrons.

b) Pyruvate/Lactate is the ...

Solution Summary

Solution includes explanation and calculations. 185 words.