Glucose metabolism proton production

Figure 2.17 Application of the reverse DEPT pulse sequence to monitor C-labeled glucose by mouse liver-cell extract. (A) Normal FT spectrum. (B) Reverse DEPT spectrum showing the a- and )3-anomeric proton resonances. (C) Two different CH2 proton resonances, a and b, appear after 1.5 h of metabolism. (D) Edited H spectrum confirming that the CH2 resonances arise from metabolic products. (Reprinted from J. Magn. Resonance 56, Brooks et al., 521, copyright 1984, Academic Press.)...

If a metabolic product is formed, the formulation of Eq. (2) indicates that an additional measurement is needed to estimate the stoichiometric coefficient (yield) of the product. Provided the product is an organic acid, such a measurement can be the amount of NH3 required for pH control when combined with the appropriate proton balance. The above cases have been examined and numerical results on characteristic systems, as well as experiments of the growth of E. coli on glucose are included in another publication (12). ... 

In animal fermentations, an organic molecule (e.g., pyruvate) serves as a terminal proton and electron acceptor, forming an organic end product (e.g., lactate). In contrast, 02 is required as a terminal acceptor for the complete oxidation of substrates such as glucose, glycogen, fatty acids, or amino acids. As discussed in chapter 3, 02 was not always available as one of the substrates for oxidative metabolism and organisms in primordial times had to rely on anaerobic metabolic processes. 

Fig. 1 Oxidative metabolism and energy production by mitochondria. The oxidation of pyruvate and free fatty acids (FFA) inside mitochondria produces NADH and FADH2, which transfer their electrons to the mitochondrial respiratory chain. The flow of electrons in mitochondrial complexes I, III, and IV is coupled with the extrusion of protons from the mitochondrial matrix into the intermembrane space. When energy is needed, these protons reenter the matrix through ATP synthase, to generate ATP from ADP. The adenine nucleotide translocator (ANT) then exchanges the formed ATP for cytosolic ADP. G-6-P Glucose 6-phosphate, PDH pyruvate dehydrogenase, LCFA-CoA long-chain fatty acyl-CoA, CPTI carnitine palmitoyltransferase I, TCA cycle tricarboxylic acid cycle, c cytochrome c...

---