Near-equilibrium enzymatic flux transfer networks

Near-equilibrium enzymatic flux transfer networks are intra-cellular mechanisms for moving ATP and a wide range of other metabolites around the cell from where they are produced to where they are needed, at a rate faster than simple diffusion through the cell's cytoplasm would be able to manage. They can act as a buffer system, as there are linear arrays of pathways with several intermediates in the chain, making the supply of metabolites more reliable. A set of parallel shuttles is also less sensitive to disruption than a single shuttle would be. This allows for automatic coupling between supply and demand, and they can almost instantly supply of a ligand to parts of cells that require it. Hence the concentrations of enzymes in the cell is very large, instead of the concentration of metabolites/solutes in the cell being large, which helps osmotic homeostasis, and means transport of metabolites is not dependent on wastefully large concentration gradients. This means that they are less costly in terms of energy used.

References

• Review: Phosphotransfer networks and cellular energetics, Petras P. Dzeja and Andre Terzic – The Journal of Experimental Biology 2003, Vol. 206, pp2039-2047