Metabolic Control Analysis (MCA) provides an understanding how changes in individual reactions propagate through an entire biochemical network. For that we calculate:
Elasticities quantify how sensitively each reaction rate responds to infinitesimal changes in metabolite concentrations or kinetic parameters. This is a local property.
Flux control coefficients measure how strongly a reaction influences the steady‑state fluxes of the entire metabolic network. This is a global property.
Concentration control coefficients describe how perturbing a reaction affects the steady‑state concentrations of metabolites throughout the system. This is a global property.
COPASI can perform a Metabolic Control Analysis (MCA) on your model.
You can find the MCA task under Tasks → Metabolic Control Analysis.
To perform a full Metabolic Control Analysis (MCA), which includes calculation of both elasticities and control coefficients, COPASI first needs the system to be at steady state. Otherwise, only the elasticities can be determined. If you have not already run a Steady-State analysis and ensured the system is at steady state, enable the checkbox that instructs COPASI to perform a Steady-State calculation before proceeding with MCA. Depending on whether COPASI must run a Steady-State analysis or not, you may be able to adjust parameters that affect how both the MCA and Steady-State are computed. For more details about these settings, refer to the Steady-State analysis section.
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| MCA Task Dialog |
To start the analysis, click the Run button. After the calculation concludes, COPASI automatically opens the Results dialog. This dialog contains three tabs: Elasticities, Flux Control Coefficients, and Concentration Control Coefficients.
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| MCA Results at Steady-State |
If a steady state was not found, only the Elasticities tab may be available. COPASI will indicate the status of the steady-state search just above the result tabs. For all results, you can choose to have COPASI display values in either scaled or unscaled form.
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| MCA Results when no Steady-State was found, only Elasticities are displayed. |
To obtain output from the MCA, you must connect the report to an output file. You can either create a custom report as described elsewhere or use the default report. The default report outputs all computed matrices as well as the steady-state results (if a steady-state calculation was performed).
To write the report to a specific file, click the Report button, which opens a dialog allowing you to associate a specific MCA task report with a disk file. First, select a suitable report for the MCA task from the dropdown menu at the top of the dialog (the default is called Metabolic Control Analysis). Next, click the browse button to choose the output file’s location. By default, COPASI creates a new file or overwrites an existing file with the specified name. Alternatively, you can have COPASI append the report to the end of an existing file by selecting the Append checkbox at the bottom of the dialog. When finished, click Confirm. Now, when you run the task, COPASI will save the output to your chosen file.
