Anabolic half reaction

Using growing CHO 320 cells as the example of the advocated method, the growth reaction given in Equation (13) is divided into two half-reactions, namely the catabolic half-reaction. Equation (18), and the anabolic half-reaction. Equation (19),... 

The criteria for the separation are well-established (see Reference [105] for details) but, for the genetically engineered cells used in this example, the anabolic half-reaction is taken to include both (i) substrate degradation to form biosynthetic precursors and (ii) the subsequent syntheses from them of the diverse macroinolecules constituting the biomass and the heterologous protein, IFN-y. For the reason stated in Section 5 2.4, carbon dioxide was incorporated into the right hand side of this half-reaction, together with the consequent H2O. Equation (19) implicitly involves the relation [105],... 

The enthalpy change for the anabolic half-reaction is neglected on good circumstantial evidence for microbes reviewed in References [18,105], In one case, it can be seen from the calculations that there is a small but significant enthalpy of anabolism for cultured Saccharoniyces ccrevisiac cells [27] but, even so, the assumption in Equation (20) would only fail by a few percent. 

Figure 53. Half cycles in dissipative maintenance metabolism with steady state ATP turnover, decoupled by futile cycling. The fhictose 6-phosphate/fructose 1,6-bisphosphate cycle is shown as an example. The net enthalpy change is calculated from the net biochemical change which, at steady state levels of ATP and all anabolic intermediates, is exclusively due to the catabolic half cycle reaction, equivalent to uncoupled catabolism (oxycaloric equivalent), Enthalpy is intermittently conserved in endothermic half cycles (p, phosphorylation a, anabolic), but an equivalent amount of enthalpy is exothermic in the reversed exergonic half cycles (-p, dephosphorylation d, dissipative). Therefore, ATP turnover and futile cycling raise the heat flux strictly proportional to the catabolic flux which, however, can be augmented by anaerobic catabolism with a corresponding anaerobic contribution to total heat flux (Reproduced from Reference [25] with permission).

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