Metabolic flux analysis

Metabolic flux analysis (MFA) is an experimental fluxomics technique used to examine production and consumption rates of metabolites in a biological system.

Nuclear magnetic resonance (NMR) techniques and mass spectrometry may then be used to measure metabolite labeling patterns to provide information for determination of pathway fluxes.

This technique for flux quantitation is applicable under metabolic and isotopic steady-state,[13] two conditions that assume that metabolite concentrations and isotopomer distributions are not changing over time, respectively.

Knowledge of the stoichiometric matrix (S) comprising the consumption and production of metabolites within biochemical reactions is needed to balance fluxes (v) around the assumed metabolic network model.

[14] Although isotopically stationary MFA allows precise deduction of metabolic fluxes through mathematical modeling, the analysis is limited to batch cultures during the exponential phase.

Similar to isotopically stationary MFA, this method requires mass and isotopomer balances to characterize the stoichiometry and atom transitions of the metabolic network.

TMFA takes into consideration only pathways and fluxes that are feasible by using the Gibbs free energy change of the reactions and activities of the metabolites that are part of the model.

[19] Examples of MFA software include 13CFLUX2[20] and OpenFLUX,[21] which evaluate 13C labeling experiments for flux calculation under metabolic and isotopically stationary conditions.

[23] By directly measuring enzymatic reaction rates, MFA can capture the dynamics of cells' behavior and metabolic phenotypes in bioreactors during large-scale fermentations.

Example of metabolic flux map for metabolic pathways of astrocytes and neurons.
Simplified workflow of an example isotope labeling experiment. The black circle in the glucose tracer represents a labeled carbon atom, while the blue atoms represent an unlabeled carbon atom.