I noticed 13% -1Corbon, 27% -2 Carbons, 15%-3Carbons, 10%-4Carbons and 4%-5Carbons coming from Glucose to Glutamate in the TCA cycle noted by isotope tracer studies. Please explain the mechanism of how it happened.
There is no exact stoichiometry for any large cycle in metabolic networks. You can write out the system of equations for all the potential metabolites, then you need to add the recycle equations (including oxidative phosphorylation and PMF build up from NADH recycle). You will end up with more equations than unknowns, which implies an infinite number of solutions. To this system you need to add the sum of the free energies of all the reactions Delta Gr ≤ 0 to get the reactions to proceed, again, the inequality isn't sufficient to define a unique solution, only a boundary beyond which certain stoichiometries can't exist. This issue is called metabolic uncoupling. An example of this (for mixed acid fermentation), which explains the issues in biochemical stoichiometries, is provided in Schneider, LV, Biological Engineering: The unit operations and mathematical modeling of biology, Chp 2, (LVS Sciences, Houston, 2022). You can also look at the online lecture from this book (https://www.youtube.com/watch?v=6r9MVzwxdAs)
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