Before revision:  We illustrate our approach on the central carbon metabolism of Escherichia coli , and on a larger metabolic model of human hepatocytes , and study the proposed graphs under various environmental conditions and genetic perturbations .
After revision:  We illustrate our approach on the central carbon metabolism of Escherichia coli and on a larger metabolic model of human hepatocytes , and study the proposed graphs under various environmental conditions and genetic perturbations .