RT Journal Article T1 Experimental test of a method for determining causal connectivities of species in reactions A1 Sánchez Torralba, Antonio A1 Yu, Kristine A1 Shen, Peidong A1 Oefner, Peter J. A1 Ross, John AB Theoretical analysis has shown the possibility of determining causal connectivities of reacting species and the reaction mechanism in complex chemical and biochemical reaction systems by applying pulse changes of concentrations of one or more species, of arbitrary magnitude, and measuring the temporal response of as many species as possible. This method, limited to measured and pulsed species, is given here an experimental test on a part of glycolysis including the sequence of reactions from glucose to fructose 1,6-biphosphate, followed by the bifurcation of that sequence into two branches, one ending in glycerol 3-phosphate, the other in glyceraldehyde 3-phosphate. Pulses of concentrations of one species at a time are applied to the open system in a non-equilibrium stationary state, and the temporal responses in concentrations of six metabolites are measured by capillary zone electrophoresis. From the results of these measurements and the use of the theory for their interpretation, we establish the causal connectivities of the metabolites and thus the reaction mechanism, including the bifurcation of one chain of reactions into two. In this test case of the pulse method, no prior knowledge was assumed of the biochemistry of this system. We conclude that the pulse method is relatively simple and effective in determining reaction mechanisms in complex systems, including reactants, products, intermediates, and catalysts and their effectors. The method is likely to be useful for substantially more complex systems. PB National Academy of Sciences USA SN 0027-8424 YR 2003 FD 2003 LK https://hdl.handle.net/20.500.14352/117542 UL https://hdl.handle.net/20.500.14352/117542 LA eng NO Torralba AS et al., Experimental test of a method for determining causal connectivities of species in reactions, 2003, Proc. Natl. Acad. Sci. USA, 100, 1494-1498 NO National Science Foundation NO National Institutes of Health NO Ministerio de Educación, Cultura y Deporte DS Docta Complutense RD 5 abr 2025