How many NADH molecules are produced per turn of the Citric Acid Cycle?

In one full turn of the Citric Acid Cycle, three NADH molecules are produced. This occurs at specific points during the cycle where NAD+ (nicotinamide adenine dinucleotide) is reduced to NADH through enzyme-catalyzed reactions.

First, the conversion of isocitrate to alpha-ketoglutarate involves the NAD+-dependent enzyme isocitrate dehydrogenase, resulting in the formation of one NADH. Next, the transformation of alpha-ketoglutarate to succinyl-CoA, facilitated by the alpha-ketoglutarate dehydrogenase complex, produces another NADH. Finally, during the conversion of malate to oxaloacetate, the enzyme malate dehydrogenase again reduces NAD+ to NADH, yielding the third molecule.

The production of these three NADH molecules is significant, as they play a crucial role in the electron transport chain, contributing to ATP synthesis during oxidative phosphorylation. Each NADH generated from the Citric Acid Cycle can ultimately lead to a substantial yield of ATP through subsequent electron transport processes.