Question 19.4: Identify the substrate, product, and coenzyme in the reactio...
Identify the substrate, product, and coenzyme in the reaction shown below. The reaction is catalyzed by the enzyme alcohol dehydrogenase.
Ethanol + NAD^+ \longrightarrow Acetaldehyde + NADH + H^+ANALYSIS Identify which molecules have been changed and how, starting from the left side of the arrow (the beginning of the reaction) to the right side of the arrow (the end of the reaction). In this case, ethanol is oxidized to acetaldehyde and NAD^+ is reduced to NADH/H^+. Recognize that nicotinamide adenine dinucleotide (NAD^+) is a coenzyme involved in oxidation/reduction reactions.
Since NAD^+ is a coenzyme involved in oxidation/reduction reactions, ethanol (the other molecule on the left side of the equation) is the substrate and acetaldehyde (on the right side of the arrow) is the product of the reaction. NADH + H^+ is the reduced form of nicotinamide adenine dinucleotide and is considered to be reduced coenzyme only—not a product of the reaction.