What is the total yield of Nicotinamide adenine dinucleotide (NADH), Flavin adenine dinucleotide (FADH₂), and Adenosine triphosphate (ATP) or Guanosine triphosphate (GTP) from the complete oxidation of 2 moles of Acetyl-Coenzyme A (acetyl-CoA) via the Citric Acid Cycle (Krebs cycle)?

From the Research

The complete oxidation of 2 mol of acetyl-CoA via the citric acid cycle yields a total of 6 mol NADH, 2 mol FADH₂, and 2 mol GTP. For each mol of acetyl-CoA that enters the cycle, the following reactions occur:

• isocitrate dehydrogenase produces 1 NADH
• α-ketoglutarate dehydrogenase produces 1 NADH
• succinate thiokinase produces 1 GTP
• succinate dehydrogenase produces 1 FADH₂
• malate dehydrogenase produces 1 NADH. Therefore, each turn of the cycle generates 3 NADH, 1 FADH₂, and 1 GTP per acetyl-CoA, as discussed in the review of the citric acid cycle and its role in metabolism 1. With 2 mol of acetyl-CoA, the cycle turns twice, doubling these yields. These reduced coenzymes (NADH and FADH₂) subsequently enter the electron transport chain where NADH yields approximately 2.5 ATP each and FADH₂ yields approximately 1.5 ATP each through oxidative phosphorylation, while each GTP is energetically equivalent to one ATP. Considering the electron transport chain, the total ATP yield from 2 mol of acetyl-CoA would be:
• 6 mol NADH * 2.5 ATP/NADH = 15 ATP
• 2 mol FADH₂ * 1.5 ATP/FADH₂ = 3 ATP
• 2 mol GTP = 2 ATP, resulting in a total of 20 ATP.