Localization of first and last enzymes in E.coli EFPs. A. pentose phosphate pathway (PPP) is used to illustrate the construction of elementary flux patterns from E.coli biochemical pathways. Localized enzymes and their associated images are shown in green. Two subsystems are considered –sub1 and sub2– and correspond to the oxidative and reversible parts of the PPP. B. These subsystems lead to four EFPs. The end-product of EFPs b, c, d, are metabolites that feed into glycolysis. Enzymes are indicated by blue arrows with their associated gene names. Localized enzymes are shown in green and diffuse enzymes in blue. Black squares are carbohydrates and circles indicate other metabolites, both identified by numbers in the legend. : 1. Glucose-6-phosphate 2. 6-phosphogluconolactone 3. 6-phosphogluconate 4. ribulose-5-phosphate 5. xylulose- 5-phosphate 6. ribose-5-phosphate 7. Glyceraldehyde-3-phosphate 8. Sedoheptulose- 7-phosphate 9. Erythrose-4-phosphate 10. Fructose-6-phosphate 11. 2-Dehydro-3-deoxy gluconate-6-phosphate. C. Distribution of EFP lengths when at least one enzyme localized (full dots) and when more than one enzyme localized (open dots). D. Ratio that first OR last enzyme are localized to number of Elementary Flux Patterns (EFP) for lengths of 3 to 12 reactions (green), calculated ratio for randomly chosen enzymes (blue) and by randomization of localized enzymes (red). Dotted arrows represent pathways 1&2 connected via localized reactions E. Ratio that first AND last enzyme are localized to EFP length (green), calculated ratio for randomly chosen enzymes (blue) and by randomization of localized enzymes (red).