1) Go the KEGG database for metabolism. Click on Carbohydrate Metabolism. Then click on circular citric acid cycle.

2) In the top left corner, there is a pull down menu. Choose E. coli K-12 MG1655. Then click on the "Exec" button.

3) Find the enzyme numbered 1.1.1.42. What enzyme is this? Why are there two boxes with this number?

4) Go back and click on the circle labeled "isocitrate". You should see the structure of this metabolite.

5) On the isocitrate page, notice there are 3 pathways listed. Click on the other two to find where isocitrate is located. Isocitrate will be highlighted as a red dot.

6) Go back to the isocitrate page. Click on the link called 1.1.1.41. What is this enzyme? Why does it have a different number?

Discovery Questions