Fission pathway: protocatechuate 2,3-cleavage pathway
type: Pathway
id: P00012
name: protoc_23
funneling branch: protocatechuate 2,3-cleavage branch
pathway component: protocatechuic acid → (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde
pathway component: (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde → (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
pathway component: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate → (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
pathway component: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate → (3E)-2-oxohex-3-enedioate
pathway component: (3E)-2-oxohex-3-enedioate → (2Z)-2-hydroxypenta-2,4-dienoate
pathway component: 2-oxopent-4-enoate → 4-hydroxy-2-oxopentanoate
pathway component: 4-hydroxy-2-oxopentanoate → acetaldehyde
pathway component: acetaldehyde → acetyl-CoA
pathway order: BiochemicalPathwayStep
  step conversion: protocatechuic acid → (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde
  reac id: R00032
  step order: 1
  next step: (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde → (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
pathway order: BiochemicalPathwayStep
  step conversion: (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde → (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
  reac id: R00033
  step order: 2
  next step: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate → (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
pathway order: BiochemicalPathwayStep
  step conversion: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate → (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
  reac id: R00034
  step order: 3
  next step: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate → (3E)-2-oxohex-3-enedioate
pathway order: BiochemicalPathwayStep
  step conversion: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate → (3E)-2-oxohex-3-enedioate
  reac id: R00059
  step order: 4
  next step: (3E)-2-oxohex-3-enedioate → (2Z)-2-hydroxypenta-2,4-dienoate
pathway order: BiochemicalPathwayStep
  step conversion: (3E)-2-oxohex-3-enedioate → (2Z)-2-hydroxypenta-2,4-dienoate
  reac id: R00060
  step order: 5
  next step: 2-oxopent-4-enoate → 4-hydroxy-2-oxopentanoate
pathway order: BiochemicalPathwayStep
  step conversion: 2-oxopent-4-enoate → 4-hydroxy-2-oxopentanoate
  reac id: R00029
  step order: 6
  next step: 4-hydroxy-2-oxopentanoate → acetaldehyde
pathway order: BiochemicalPathwayStep
  step conversion: 4-hydroxy-2-oxopentanoate → acetaldehyde
  reac id: R00030
  step order: 7
  next step: acetaldehyde → acetyl-CoA
pathway order: BiochemicalPathwayStep
  step conversion: acetaldehyde → acetyl-CoA
  reac id: R00031
  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: caffeic acid
  type: PathwayConnection
  direction: upstream
  id: P00018
  pathway type: Funneling
  connecting substrate id: S00002
connections: m-cresol
  type: PathwayConnection
  direction: upstream
  id: P00021
  pathway type: Funneling
  connecting substrate id: S00002
connections: p-cresol
  type: PathwayConnection
  direction: upstream
  id: P00024
  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: 2026-02-28T10:42:00.368700+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 → (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde
type: BiochemicalReaction
id: R00032
left: protocatechuic acid
right: (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde
catalysis: Catalysis
  controller: protocatechuate 2,3-dioxygenase
  controlled: protocatechuic acid → (2Z,4Z)-2-hydroxy-5-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 2,3-dioxygenase
type: Protein
id: E00024
EC number: 1.13.11.-
xref: UnificationXref
  db: UniProt
  id: C4TP01

(2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde → (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
type: BiochemicalReaction
id: R00033
left: (2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde
right: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
comment: This reaction can occur spontaneously

(2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate → (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
type: BiochemicalReaction
id: R00034
left: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
right: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
catalysis: Catalysis
  controller: 2-hydroxymuconate-6-semialdehyde dehydrogenase
  controlled: (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate → (2Z,4E)-2-hydroxyhexa-2,4-dienedioate

2-hydroxymuconate-6-semialdehyde dehydrogenase
type: Protein
id: E00025
EC number: 1.2.1.85

(2Z,4E)-2-hydroxyhexa-2,4-dienedioate → (3E)-2-oxohex-3-enedioate
type: BiochemicalReaction
id: R00059
left: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate
right: (3E)-2-oxohex-3-enedioate
catalysis: Catalysis
  controller: 4-oxalocrotonate tautomerase
  controlled: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate → (3E)-2-oxohex-3-enedioate

4-oxalocrotonate tautomerase
type: Protein
id: E00053

(3E)-2-oxohex-3-enedioate → (2Z)-2-hydroxypenta-2,4-dienoate
type: BiochemicalReaction
id: R00060
left: (3E)-2-oxohex-3-enedioate
right: (2Z)-2-hydroxypenta-2,4-dienoate
catalysis: Catalysis
  controller: 2-oxo-3-hexenedioate decarboxylase
  controlled: (3E)-2-oxohex-3-enedioate → (2Z)-2-hydroxypenta-2,4-dienoate

2-oxo-3-hexenedioate decarboxylase
type: Protein
id: E00054

2-oxopent-4-enoate → 4-hydroxy-2-oxopentanoate
type: BiochemicalReaction
id: R00029
left: 2-oxopent-4-enoate
right: 4-hydroxy-2-oxopentanoate
catalysis: Catalysis
  controller: 2-oxopent-4-enoate hydratase
  controlled: 2-oxopent-4-enoate → 4-hydroxy-2-oxopentanoate

2-oxopent-4-enoate hydratase
type: Protein
id: E00022
EC number: 4.2.1.80

4-hydroxy-2-oxopentanoate → acetaldehyde
type: BiochemicalReaction
id: R00030
left: 4-hydroxy-2-oxopentanoate
right: acetaldehyde
right: pyruvate
catalysis: Catalysis
  controller: 4-hydroxy-2-oxovalerate aldolase
  controlled: 4-hydroxy-2-oxopentanoate → acetaldehyde

4-hydroxy-2-oxovalerate aldolase
type: Protein
id: E00023
EC number: 4.1.3.39

acetaldehyde → acetyl-CoA
type: BiochemicalReaction
id: R00031
left: acetaldehyde
right: acetyl-CoA