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Record Information
StatusExpected but not Quantified
Creation Date2010-07-16 13:49:07 UTC
Update Date2020-02-26 21:38:58 UTC
Secondary Accession Numbers
  • HMDB13636
Metabolite Identification
Common NamePyrroloquinoline quinone
DescriptionPyrroloquinoline quinone, also known as coenzyme PQQ or methoxatin, belongs to the class of organic compounds known as pyrroloquinoline quinones. Pyrroloquinoline quinones are compounds with a structure based on the 2,7,-tricarboxy-1H-pyrrolo[2,3-f ]quinoline-4,5-dione. Pyrroloquinoline Quinones usually bear a carboxylic acid group at the C-2, C-7 and C-9 positions. A glutamic acid and a tyrosine in PqqA are cross-linked by the radical SAM enzyme PqqE in the first step of PqqA modification. Pyrroloquinoline quinone is a drug. A novel aspect of PQQ is its biosynthesis in bacteria from a ribosomally translated precursor peptide, PqqA. Pyrroloquinoline quinone (PQQ), also called methoxatin, is a redox cofactor. Pyrroloquinoline quinone is an extremely weak basic (essentially neutral) compound (based on its pKa). Pyrroloquinoline quinone exists in all living organisms, ranging from bacteria to humans. PQQ stimulates growth in bacteria. In humans, pyrroloquinoline quinone is involved in disulfiram action pathway. Outside of the human body, pyrroloquinoline quinone has been detected, but not quantified in, green vegetables. This could make pyrroloquinoline quinone a potential biomarker for the consumption of these foods. Enzymes containing PQQ are called quinoproteins. Efforts to understand PQQ biosynthesis have contributed to broad interest in radical SAM enzymes and their ability to modify proteins, and an analogous radical SAM enzyme-dependent pathway has since been found that produces the putative electron carrier mycofactocin, using a valine and a tyrosine from the precursor peptide MftA.The scientific journal Nature published the 2003 paper by Kasahara and Kato that essentially stated that PQQ was a new vitamin and in 2005, an article by Anthony and Fenton that stated that the 2003 Kasahara and Kato paper drew incorrect and unsubstantiated conclusions. Anthony and Zatman also found the unknown redox cofactor in alcohol dehydrogenase. In 1979, Salisbury and colleagues as well as Duine and colleagues extracted this prosthetic group from methanol dehydrogenase of methylotrophs and identified its molecular structure. It was discovered by J.G. Hauge as the third redox cofactor after nicotinamide and flavin in bacteria (although he hypothesised that it was naphthoquinone). Glucose dehydrogenase, one of the quinoproteins, is used as a glucose sensor. Adachi and colleagues discovered that PQQ was also found in Acetobacter.
2,4,6-Tricarboxylic-pyrrolo[2,3-5,6]quinoline 8,9-quinoneChEBI
4,5-Dihydro-4,5-dioxo-1H-pyrrolo[2,3-5,6]quinoline-2,7,9-tricarboxylic acidChEBI
Coenzyme PQQChEBI
Pyrrolo-quinoline quinoneChEBI
4,5-Dioxo-4,5-dihydro-1H-pyrrolo[2,3-F]quinoline-2,7,9-tricarboxylic acidGenerator
2,7,9-Tricarboxypyrroloquinoline quinoneMeSH
Coenzyme, PQQMeSH
Cofactor, PQQMeSH
Quinone, pyrrolo-quinolineMeSH
4,5-Dihydro-4,5-dioxo-1-H-pyrrolo(2,3-F)quinoline-2,7,9-tricarboxylic acidMeSH
PQQ CoenzymeMeSH
PQQ CofactorMeSH
Quinone, pyrroloquinolineMeSH
PQQ, CoenzymeMeSH
Pyrrolo quinoline quinoneMeSH
Chemical FormulaC14H6N2O8
Average Molecular Weight330.206
Monoisotopic Molecular Weight330.012415178
IUPAC Name4,5-dioxo-1H,4H,5H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid
Traditional Namepyrroloquinoline quinone
CAS Registry Number72909-34-3
InChI Identifier
Chemical Taxonomy
Description belongs to the class of organic compounds known as pyrroloquinoline quinones. Pyrroloquinoline quinones are compounds with a structure based on the 2,7,-tricarboxy-1H-pyrrolo[2,3-f ]quinoline-4,5-dione. Pyrroloquinoline Quinones usually bear a carboxylic acid group at the C-2, C-7 and C-9 positions.
KingdomOrganic compounds
Super ClassOrganoheterocyclic compounds
ClassQuinolines and derivatives
Sub ClassPyrroloquinolines
Direct ParentPyrroloquinoline quinones
Alternative Parents
  • Pyrroloquinoline quinone
  • Quinoline-4-carboxylic acid
  • Quinoline-2-carboxylic acid
  • Indole or derivatives
  • Pyridine carboxylic acid
  • Pyridine carboxylic acid or derivatives
  • Tricarboxylic acid or derivatives
  • O-quinone
  • Pyrrole-2-carboxylic acid
  • Pyrrole-2-carboxylic acid or derivatives
  • Aryl ketone
  • Quinone
  • Pyridine
  • Substituted pyrrole
  • Heteroaromatic compound
  • Pyrrole
  • Vinylogous amide
  • Ketone
  • Azacycle
  • Carboxylic acid derivative
  • Carboxylic acid
  • Hydrocarbon derivative
  • Organic oxide
  • Organopnictogen compound
  • Organooxygen compound
  • Organonitrogen compound
  • Organic oxygen compound
  • Organic nitrogen compound
  • Aromatic heteropolycyclic compound
Molecular FrameworkAromatic heteropolycyclic compounds
External Descriptors

Biological location:

Route of exposure:



Naturally occurring process:


Industrial application:

Physical Properties
Experimental Properties
Melting PointNot AvailableNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility0.097 g/LALOGPS
pKa (Strongest Acidic)3.05ChemAxon
pKa (Strongest Basic)-3.3ChemAxon
Physiological Charge-3ChemAxon
Hydrogen Acceptor Count9ChemAxon
Hydrogen Donor Count4ChemAxon
Polar Surface Area174.72 ŲChemAxon
Rotatable Bond Count3ChemAxon
Refractivity74.53 m³·mol⁻¹ChemAxon
Polarizability28.91 ųChemAxon
Number of Rings3ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Spectrum TypeDescriptionSplash KeyView
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0rkl-1293000000-f89d3e9669ea62420001Spectrum
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (3 TMS) - 70eV, Positivesplash10-00di-5001920000-ffb897aa343201141554Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-03dr-0059000000-fe32e3dcdbb122899a9bSpectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-01p9-0093000000-0057ba82bb1928e2b729Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-00kf-0090000000-7a80db950a195ffc246aSpectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-01ti-0089000000-3940ecb0162179ef62fcSpectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-00kr-0092000000-47c12a164c99ff5da573Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-00ku-0090000000-968a80882216e4efda23Spectrum
Biological Properties
Cellular LocationsNot Available
Biospecimen LocationsNot Available
Tissue LocationsNot Available
Normal Concentrations
Not Available
Abnormal Concentrations
Not Available
Associated Disorders and Diseases
Disease ReferencesNone
Associated OMIM IDsNone
DrugBank IDDB03205
Phenol Explorer Compound IDNot Available
FooDB IDFDB012848
KNApSAcK IDNot Available
Chemspider ID997
KEGG Compound IDC00113
BioCyc IDNot Available
BiGG IDNot Available
Wikipedia LinkPyrroloquinoline quinone
METLIN IDNot Available
PubChem Compound1024
PDB IDNot Available
ChEBI ID18315
Food Biomarker OntologyNot Available
VMH IDNot Available
Synthesis ReferenceNot Available
Material Safety Data Sheet (MSDS)Not Available
General References
  1. Paz MA, Fluckiger R, Torrelio BM, Gallop PM: Methoxatin (PQQ), coenzyme for copper-dependent amine and mixed-function oxidation in mammalian tissues. Connect Tissue Res. 1989;20(1-4):251-7. [PubMed:2558842 ]
  2. Kasahara T, Kato T: Nutritional biochemistry: A new redox-cofactor vitamin for mammals. Nature. 2003 Apr 24;422(6934):832. [PubMed:12712191 ]