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. 2014 Oct 24;26(10):3847–3866. doi: 10.1105/tpc.114.130328

Table 2. Definitions of Terms Used in Metabolic Modeling.

Term Definition
Constraint A restriction that must be satisfied for a solution to be permitted. It limits and defines a space where the feasible flux distributions occur.
Elementary modes Unique sets of nondecomposable reactions within any network that are able to both sustain a steady state flux and operate independently.
Extreme pathways Unique and minimal sets of reactions within any network that correspond to the extreme rays of a polyhedral cone and therefore completely characterize the steady state capabilities of metabolic networks.
Flux distribution A specific set of reaction fluxes in a network.
Isotopic labeling experiment An experiment in which isotopically labeled precursor (generally 13C-labeled) is fed to the target, and the subsequent redistribution of the label is measured as a time course or after the system has reached an isotopic steady state.
Metabolic control analysis A means to investigate the sensitivity of the steady state properties of a network by quantitative determination of enzymatic control coefficients.
Network robustness The potential of a network to tolerate and respond to perturbation cause by a genetic and/or an environmental change.
Objective function A function that must be maximized or minimized, reducing the solution space and defining fluxes that satisfy the objective of the model.
Steady state The state wherein the quantity of a compound being produced is equal to the quantity being consumed.
Stoichiometric matrix A matrix wherein, for each reaction, the stoichiometry of the metabolism is represented by a column and each metabolite is represented by a row.