Fission pathway: protocatechuate 4,5-cleavage pathway
type: Pathway
id: P00002
name: protocatechuate45
name: protocatechuate 4,5-cleavage pathway
name: protocatechuate meta-cleavage pathway
funneling branch: beta-ketoadipate branch
pathway component: protocatechuic acid → 2-hydroxy-4-carboxymuconate-6-semialdehyde
pathway component: 2-hydroxy-4-carboxymuconate-6-semialdehyde → 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
pathway component: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal → 2-pyrone-4,6-dicarboxylate
pathway component: 2-pyrone-4,6-dicarboxylate → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
pathway component: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate → (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
pathway component: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate → 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
pathway component: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
pathway component: oxaloacetate → pyruvate
pathway order: BiochemicalPathwayStep
  step conversion: protocatechuic acid → 2-hydroxy-4-carboxymuconate-6-semialdehyde
  reac id: R00007
  step order: 1
  next step: 2-hydroxy-4-carboxymuconate-6-semialdehyde → 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
pathway order: BiochemicalPathwayStep
  step conversion: 2-hydroxy-4-carboxymuconate-6-semialdehyde → 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
  reac id: R00008
  step order: 2
  next step: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal → 2-pyrone-4,6-dicarboxylate
pathway order: BiochemicalPathwayStep
  step conversion: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal → 2-pyrone-4,6-dicarboxylate
  reac id: R00009
  step order: 3
  next step: 2-pyrone-4,6-dicarboxylate → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
pathway order: BiochemicalPathwayStep
  step conversion: 2-pyrone-4,6-dicarboxylate → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
  reac id: R00010
  step order: 4
  next step: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate → (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
pathway order: BiochemicalPathwayStep
  step conversion: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate → (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
  reac id: R00011
  step order: 5
  next step: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate → 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
pathway order: BiochemicalPathwayStep
  step conversion: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate → 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
  reac id: R00012
  step order: 6
  next step: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
pathway order: BiochemicalPathwayStep
  step conversion: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
  reac id: R00013
  step order: 7
  next step: oxaloacetate → pyruvate
pathway order: BiochemicalPathwayStep
  step conversion: oxaloacetate → pyruvate
  reac id: R00054
  step order: 8
connections: vanillin I
  type: PathwayConnection
  direction: downstream
  id: P00006
  pathway type: Funneling
  connecting substrate id: S00002
connections: vanillin II
  type: PathwayConnection
  direction: downstream
  id: P00007
  pathway type: Funneling
  connecting substrate id: S00002
connections: m-cresol
  type: PathwayConnection
  direction: upstream
  id: P00021
  pathway type: Funneling
  connecting substrate id: S00002
connections: syringic acid II
  type: PathwayConnection
  direction: upstream
  id: P00022
  pathway type: Fission
connections: p-cresol
  type: PathwayConnection
  direction: upstream
  id: P00024
  pathway type: Funneling
  connecting substrate id: S00002
connections: caffeic acid
  type: PathwayConnection
  direction: upstream
  id: P00018
  pathway type: Funneling
  connecting substrate id: S00002
connections: p-coumaric acid
  type: PathwayConnection
  direction: upstream
  id: P00014
  pathway type: Funneling
  connecting substrate id: S00002
created: 2026-02-28T10:42:00.378735+00:00
elignin note: This file is JSON-LD based on BioPAX Level 3 naming conventions. It is NOT a standards-compliant BioPAX OWL/RDF document. eLignin-specific extensions (elignin_id, connections, genes, …) are mapped to the http://www.elignindatabase.com/ontology# namespace. To convert to canonical BioPAX RDF/XML use pybiopax or a compatible RDF serialiser.

protocatechuic acid → 2-hydroxy-4-carboxymuconate-6-semialdehyde
type: BiochemicalReaction
id: R00007
left: protocatechuic acid
right: 2-hydroxy-4-carboxymuconate-6-semialdehyde
catalysis: Catalysis
  controller: protocatechuate 4,5-dioxygenase
  controlled: protocatechuic acid → 2-hydroxy-4-carboxymuconate-6-semialdehyde

protocatechuic acid
type: SmallMolecule
id: S00002
chemical formula: C7H6O4
molecular weight: 153.11
xref: UnificationXref
  db: PubChem Compound
  id: 72
xref: UnificationXref
  db: ChEBI
  id: 36062
xref: UnificationXref
  db: KEGG Compound
  id: C00230
xref: UnificationXref
  db: CAS
  id: 99-50-3

protocatechuate 4,5-dioxygenase
type: Protein
id: E00004
EC number: 1.13.11.8

2-hydroxy-4-carboxymuconate-6-semialdehyde → 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
type: BiochemicalReaction
id: R00008
left: 2-hydroxy-4-carboxymuconate-6-semialdehyde
right: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
comment: This reaction can occur spontaneously

2-hydroxy-4-carboxymuconate semialdehyde hemiacetal → 2-pyrone-4,6-dicarboxylate
type: BiochemicalReaction
id: R00009
left: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal
right: 2-pyrone-4,6-dicarboxylate
catalysis: Catalysis
  controller: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal dehydrogenase
  controlled: 2-hydroxy-4-carboxymuconate semialdehyde hemiacetal → 2-pyrone-4,6-dicarboxylate

2-hydroxy-4-carboxymuconate semialdehyde hemiacetal dehydrogenase
type: Protein
id: E00005
EC number: 1.1.1.312

2-pyrone-4,6-dicarboxylate → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
type: BiochemicalReaction
id: R00010
left: 2-pyrone-4,6-dicarboxylate
right: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
catalysis: Catalysis
  controller: 2-pyrone-4,6-dicarboxylate lactonase
  controlled: 2-pyrone-4,6-dicarboxylate → (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate

2-pyrone-4,6-dicarboxylate lactonase
type: Protein
id: E00006
EC number: 3.1.1.57

(1E)-4-oxobut-1-ene-1,2,4-tricarboxylate → (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
type: BiochemicalReaction
id: R00011
left: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
right: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
catalysis: Catalysis
  controller: 4-oxalomesaconate tautomerase
  controlled: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate → (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
comment: This reaction can occur spontaneously

4-oxalomesaconate tautomerase
type: Protein
id: E00007
EC number: 5.3.2.8

(1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate → 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
type: BiochemicalReaction
id: R00012
left: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate
right: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
catalysis: Catalysis
  controller: 4-oxalmesaconate hydratase
  controlled: (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate → 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
comment: Reaction shared between Syringate pathways I-II

4-oxalmesaconate hydratase
type: Protein
id: E00058

2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
type: BiochemicalReaction
id: R00013
left: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate
right: pyruvate
right: oxaloacetic acid
catalysis: Catalysis
  controller: oxaloacetate decarboxylase
  controlled: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
catalysis: Catalysis
  controller: HMG aldolase
  controlled: 2-hydroxy-4-oxobutane-1,2,4-tricarboxylate → pyruvate
comment: Reaction shared between Syringate pathways I-II

oxaloacetate decarboxylase
type: Protein
id: E00046
EC number: EC 4.1.1.3

HMG aldolase
type: Protein
id: E00050

oxaloacetate → pyruvate
type: BiochemicalReaction
id: R00054
left: oxaloacetate
right: pyruvate
catalysis: Catalysis
  controller: oxaloacetate decarboxylase
  controlled: oxaloacetate → pyruvate
comment: Reaction shared between Syringate pathways I-II