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DraconiticBiochemistryBiomolecules · Catabolism · Biosynthesis · Metabolism
Data

Field guide

Read the network before tracing the line: carbon exchange, energy conversion, lipid and amino-acid chemistry, nucleotide economy, cofactors, and the mechanistic scale revealed by oxalosuccinate.

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Guide chapters
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Metabolic domains
12
Pathway districts
58
Map edition
human-metabolism-r97-expanded-20261025, 2,039 events
MECHANISTIC FOCUS

Oxalosuccinate: a reaction intermediate, not a free-standing pool

The namesake compound is most useful as a lesson in scale: a net pathway arrow can conceal chemically meaningful enzyme-bound steps.

Two-dimensional structure of isocitrateIsocitratealcohol substrate · C₆
Two-dimensional structure of oxalosuccinate(S)-Oxalosuccinateβ-keto intermediate · C₆
Two-dimensional structure of 2-oxoglutarate2-Oxoglutarate + CO₂product · C₅
Oxalosuccinate appears inside the oxidative-decarboxylation sequence, where its carbonyl and β-keto-acid chemistry can be read.

Mitochondrial NADP-dependent isocitrate dehydrogenase couples oxidation of isocitrate to reduction of NADP+, then decarboxylates the oxidized intermediate. Rhea represents both the overall reaction and stepwise chemistry involving charge-specific (S)-oxalosuccinate.

The map therefore shows oxalosuccinate inside a mechanistic inset rather than as a large shared metabolite station. That visual choice keeps a transient intermediate from being mistaken for an independently measured cellular pool.

The NAD-dependent IDH3 route and NADP-dependent IDH2 route remain distinct because their cofactors, enzyme assemblies and physiological contexts are not interchangeable even when their displayed carbon products overlap.

Ideas to carry into the map

  1. Net reactions can conceal ordered steps.
  2. Charge and stereochemistry are part of chemical identity.
  3. Shared products do not make cofactor-specific routes equivalent.

Pathways in this field note

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