I know that glycolysis is an universal metabolic pathway, even some variations can appears in some species / taxonomic groups / kingdoms. Why different literature report fluctations in ATP global production (from 32-38 ATP molecules from each glucose molecule) after aerobic glycolysis + Krebs Cycle + Respiratory chain + Oxidative phosphorilation? Is there any thermodinamics or molecular bases for justifying such variations?
Dear Frenkel,
Attached please find our recent paper on this topic which covers the answer to your question.
ATP molecules are formed from ADP and Pi. This is called ATP synthesis by chemiosmosis [1].
Table 1 summarizes the glucose breakdown stages as illustrated in Figure 3; out of the 36 or 38 ATP formed by complete glucose breakdown, 4 are the result of substrate-level ATP synthesis and the 32 or 34 are produced as a result of the electron transport chain. Out of NADH produced, four are the result of substrate-level ATP synthesis and the rest are produced as a result of the electron transport chain. For most NADH molecules that donate electrons to the electron transport chain, 3 ATP molecules are produced. However, in some cells, each NADH formed in the cytoplasm results in only 2 ATP molecules because a shuttle, rather than NADH, takes electrons through the mitochondrial membrane. FADH2 results in the formation of only 2 ATP because its electrons enter the electron transport chain at a lower energy level [1].
Table 1. Summary of glucose breakdown as shown in Figure 3.
Pathway
Substrate-Level
Phosphorylation
Oxidative
Phosphorylation
Total
ATP
Glycolysis
2 ATP
2 NADH = 4 - 6 ATP
6-8
CoA
2 NADH = 6 ATP
6
Citric acid cycle
2 ATP
6 NADH = 18 ATP
2 FADH2 = 4 ATP
24
Total
4 ATP
32 ATP
36-38
Hoping this will be helpful,
Rafik