Biochemical reactions yield coefficients

Since many biochemical reactions and their stoichiometry are not well understood, we often find a more empirical approach to the quantitative assessment of the kinetics. Mass concentration units (e.g., g/L) are often used along with yield coefficients to calculate the distribution of products formed and the amount of substrate consumed. In the absence of any inhibition effects and in the presence of an infinite supply of substrate, the rate of cell growth rx is autocatalytic, that is, it depends only on the concentration of cells (Cx), and the more cells we have, the higher the growth rate. The cell biomass is typically represented by X ... 

An overall yield coefficient, Fx/s is defined as the ratio of the total amount of new product X obtained (in mass or moles) per unit consumption of substrate S (again in mass or moles) over the entire course of a biochemical reaction. 

At this stage, we must make the following important observation regarding the Z-scheme for photosynthesis (summarizing all the primary biochemical reactions of the metabolism, ie, the light reactions of photosynthesis). If we consider only the stoichiometric photons involved in this scheme, then we can simply define the mean quantum yield using the data on the stoichiometric coefficient v o-x, direcdy Unked by the structured equations (eg, Eq. (121)) to the stoichiometric coefficient Vmadph,h -x and to the value of the P/2e ratio from... 

As this example shows, stoichiometric network analysis yields only possibilities of reaction mechanisms, it does not lead to the determination of which of many possible reaction pathways corresponds to experiments. We need to know the rate coefficients of the system to determine paths in the system by which reactants proceed to form products. This distinction has been overlooked in a number of studies on complex biochemical reacdon mechanisms (see Schilling et al. [82] and references therein). 

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