Question 22.4: Coenzymes Describe the reactive part of each of the followin......

a. The oxidized form of FAD undergoes reduction when two nitrogen atoms in the flavin part react with $2 H ^{+}$ and $2\ e^{-}$ to give $FADH _2$. The coenzyme FAD is utilized in oxidation reactions that produce carbon-carbon double bonds (C=C).

b. The oxidized form of $NAD ^{+}$ undergoes reduction when a carbon atom in the nicotinamide part reacts with $2 H ^{+}$ and $2\ e^{-}$, to give NADH and $H ^{+}$. The coenzyme $NAD ^{+}$ is utilized in oxidation reactions that produce carbon-oxygen double bonds (C=O).