Would anyone have ever seen a diagram of the Krebs cycle clearly identifying the two carbon atoms coming from acetylCoA and then released in the form of CO2?
I’ve been writing the developed formulas of all intermediaries to better understand what goes on in between each reaction, and I’m confused. My textbook says that the CO2 eliminated by isocitrate dH and alpha-cetoglutarate dH come from the acetylCoA added to oxaloacetate at the start of the cycle and that from succinyl-CoA onwards, it can be said that the acetylCoA has already been fully eliminated.
However, if I properly understood the reaction catalysed by citrate synthase, then the two carbons from acetylCoA simply latch onto the C1 of oxaloacetate, whose carboxylic and ketone functions becomes citrate’s OH-C-COOH in C3. Then, when moving from oxalosuccinate to alpha-cetoglutarate, it looks like the released CO2 comes from the COOH in C3, i.e. the original carboxylic function in oxaloacetate, and not from acetylCoA whose two carbons are still there(C1 and C2).
It’s hard to describe without drawing it, especially with my very lacking command of nomenclature (an area barely touched upon in my curriculum), but I hope someone can understand what my problem is.