Isocitrate to malate in two steps, a shortcut around the CO₂-releasing steps of the Krebs cycle
Route: Isocitrate → Glyoxylate + Succinate → Malate
Isocitrate lyase splits isocitrate into succinate and glyoxylate. Malate synthase joins glyoxylate to the two carbons of acetyl-CoA and gives malate. Compared with the Krebs cycle, the two decarboxylation steps are skipped, so the carbons of acetyl-CoA stay in four-carbon compounds that can be used to build sugars and other molecules. Succinate and malate both belong to the Krebs cycle, which links the two cycles. Both enzymes are found in plants, bacteria and fungi. Mammals lack a pathway for the net production of sugar precursors from acetyl-CoA.
Practice this pathway All pathways
| Step | Enzyme | EC | In | Out |
|---|---|---|---|---|
| 1 | Isocitrate lyase | 4.1.3.1 | ||
| 2 | Malate synthase | 2.3.3.9 | Acetyl-CoA | CoA-SH |
Enzyme names and EC numbers are those used on the interactive board. Checked against sources: see the claim table in the repository (tools/pathway_data/checks).