The technology to genetically engineer specific steps in metabolism has advanced rapidly during the last decade. The advent of "metabolic engineering" to create transgenic organisms with altered metabolism requires that technologies also be developed to evaluate the metabolic fluxes that occur within these transgenic organisms relative to wild-type. Stable isotope and radioisotope tracer methods for monitoring the labeling kinetics of intermediates in metabolic pathways are well established tools that can be readily applied to these problems. However, the utility of these isotopic tracer methods is greatly enhanced when the resulting isotopic kinetic data is analyzed quantitatively with computer models. This site describes some simple computer routines that can be used to interpret stable isotope and radioisotope tracer kinetics in terms of metabolic fluxes and compartmentation of pools.

• Introduction
• Effects of Varying Rates and Pool Sizes - A Sample Program
• Consideration of Multiple Compartments
• Consideration of Cycles - The GS/GOGAT Cycle
• Compounds Receiving Several ¹³C Atoms from ¹³CO₂
• Isotopomers of the Citric Acid Cycle Supplied with 3-¹³C-Pyruvate
• Modeling Radioactive Precursor Uptake Kinetics
• Simulation of The Pathway of DMSP Biosynthesis in Enteromorpha intestinalis
• Simulation of The Pathway of Synthesis of DMSP in Spartina alterniflora
• Making Rates Linearly or Hyperbolically Responsive to Pool Size Changes
• Metabolic Engineering of Glycine Betaine Synthesis - Metabolism of ¹⁴C-Choline in Transgenic Tobacco Expressing Choline Monooxygenase in the Chloroplast
• Considering Feedback Inhibition
• Modeling Allosteric Behavior - Cooperative Substrate Binding
• Links to Other Metabolic Modeling Resources on the www
• References
• Sponsors