Calculate and compare the AGº' values for the oxidation of succinate by NAD and FAD. Use the data given in the table to findthe E' of the NAD: NADH and fumarate:succinate couples, and assume that E' for the enzyme-bound FAD : FADH₂ redox+couple is nearly +0.05 V.OxidantNAD+FumarateReductantNADH + HSuccinate+AGO for the oxidation of succinate by NADAGO for the oxidation of succinate by FAD:n2E'o (V)-0.32T-0.03+FAD is an oxidant, whereas NAD is a reductant.+Why is FAD rather than NAD the electron acceptor in the reaction catalyzed by succinate dehydrogenase?+The oxidation of succinate by NAD is not thermodynamically feasible.+The oxidation of succinate requires two NAD molecules but only one FAD molecule.+The electron-transport chain can regenerate FAD, but not NAD˚.kJ mol-¹-1kJ mol-¹

Calculation for balance cell reaction using Nernst equationHalf reactions (Reduction) NAD + 2H+ + 2e- NADH + H+ (Oxidation) Succinate Fumerate + 2H+ + 2e- Overall reaction: Succinate + FAD Fumerate + FADH2 for oxidation of succinate by NAD+We known=2F = 96.5 KJ mol-155.97 KJ mol-1Half reactions (Reduction) FAD + 2H+ + 2e- FADH2 (Oxidation) Succinate Fumerate + 2H+ + 2e- Overall reaction: Succinate + FAD Fumerate + FADH2 for oxidation of succinate by FADWe known=2F = 96.5 KJ mol-1-15.44 KJ mol-1Correct answer 1: The oxidation of succinate by NAD+ is not thermodynamically feasible.Explanation: Succinate is converted into fumarate with the enzyme succinate dehydrogenase with FAD. This FAD acts hydrogen acceptor by accepting two hydrogen and 2e- gets reduced to form FADH2. In case of NAD+ which is also reducing agent like FAD. NAD+ can not accept two electrons and does not meet the energy requirement to get reduced.Incorrect answer 2: NAD+ requires more energy than FAD and two will be more difficult to reduced.Incorrect answer 3: FAD and NAD+ can be regenerated by donating H+ and e-.Incorrect answer 4: Both NAD+ and FAD play role in oxidation and they act as reducing agents.for oxidation of succinate by NAD+55.97 KJ mol-1for oxidation of succinate by FAD+-15.44 KJ mol-1 Correct answer 1: "The oxidation of succinate by NAD+ is not thermodynamically feasible".