The chapter begins with a seemingly appropriate model of purine metabolism. It soon becomes evident that the model cannot be correct. A better model is constructed, accounting for the former problems. Systematic analysis shows that the model is indeed better but still not satisfactory. Diagnostic tools, introduced in earlier chapters are applied to pinpoint the locations of problems.
Focused amendments improve the performance of the model, but the model still exhibits problems.
After several steps in this modeling sequence, a feasible model is obtained. This model is analyzed and evaluated. This case emphasizes algebraic analyses as they are learned in Chapters 6 and 7. An actual branched pathway is formulated as an S-system model. Parameters are estimated from information in the literature.