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Record Information
Creation Date2014-10-02 19:00:48 UTC
Update Date2018-03-21 17:46:21 UTC
Accession NumberT3D4965
Common Name1-Pyrroline-5-carboxylic acid
ClassSmall Molecule
Description1-Pyrroline-5-carboxylic acid is an enamine or an imino acid that forms upon the spontaneous dehydration of L-glutamate gamma-semialdehyde in aqueous solutions. The stereoisomer (S)-1-pyrroline-5-carboxylate is an intermediate in glutamate metabolism, arginine degradation, and proline biosynthesis and degradation. It can also be converted into or be formed from three amino acids: L-glutamate, L-ornithine, and L-proline. In particular, it is synthesized via the oxidation of proline by pyrroline-5-carboxylate reductase 1 (PYCR1) (EC or by proline dehydrogenase (PRODH) (EC It is hydrolyzed to L-glutamate by delta-1-pyrroline-5-carboxylate dehydrogenase (ALDH4A1) (EC It is also one of the few metabolites that can act as a precursor to other metabolites of both the urea cycle and the tricarboxylic acid (TCA) cycle. Under certain conditions, pyrroline-5-carboxylate can act as a neurotoxin and a metabotoxin. A neurotoxin causes damage to nerve cells and nerve tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of pyrroline-5-carboxylate are associated with at least five inborn errors of metabolism, including hyperprolinemia type I, hyperprolinemia type II, iminoglycinuria, prolinemia type II, and pyruvate carboxylase deficiency. Hyperprolinemia type II results in high levels of pyrroline-5-carboxylate. People with hyperprolinemia type II have signs and symptoms that vary in severity, but they are more likely than type I to have seizures or intellectual disability. Pyrroline-5-carboxylate is highly reactive and excess quantities have been shown to cause cell death and apoptosis (PMID: 15548746).
Compound Type
  • Animal Toxin
  • Metabolite
  • Natural Compound
Chemical Structure
3,4-Dihydro-2h-pyrrole-2-carboxylic acid
D1-Pyrroline-5-carboxylic acid
delta-1-Pyrroline-5-carboxylic acid
DL-1-Pyrroline-5-carboxylic acid
L-delta 1-Pyrroline-5-carboxylate
Pyrroline 5-carboxylate
Chemical FormulaC5H7NO2
Average Molecular Mass113.115 g/mol
Monoisotopic Mass113.048 g/mol
CAS Registry Number2906-39-0
IUPAC Name3,4-dihydro-2H-pyrrole-2-carboxylic acid
Traditional Name1-pyrroline-5-carboxylic acid
InChI IdentifierInChI=1/C5H7NO2/c7-5(8)4-2-1-3-6-4/h3-4H,1-2H2,(H,7,8)
Chemical Taxonomy
Description belongs to the class of organic compounds known as alpha amino acids and derivatives. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon), or a derivative thereof.
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassAmino acids, peptides, and analogues
Direct ParentAlpha amino acids and derivatives
Alternative Parents
  • Alpha-amino acid or derivatives
  • Pyrroline carboxylic acid
  • Pyrroline carboxylic acid or derivatives
  • Pyrroline
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Propargyl-type 1,3-dipolar organic compound
  • Organic 1,3-dipolar compound
  • Organoheterocyclic compound
  • Azacycle
  • Organopnictogen compound
  • Organic oxygen compound
  • Organooxygen compound
  • Organonitrogen compound
  • Organic oxide
  • Carbonyl group
  • Imine
  • Organic nitrogen compound
  • Hydrocarbon derivative
  • Aliphatic heteromonocyclic compound
Molecular FrameworkAliphatic heteromonocyclic compounds
External Descriptors
Biological Properties
StatusDetected and Not Quantified
Cellular Locations
  • Mitochondria
Biofluid LocationsNot Available
Tissue Locations
  • Intestine
PathwaysNot Available
ApplicationsNot Available
Biological RolesNot Available
Chemical RolesNot Available
Physical Properties
AppearanceWhite powder.
Experimental Properties
Melting PointNot Available
Boiling PointNot Available
SolubilityNot Available
LogPNot Available
Predicted Properties
Water Solubility13.1 g/LALOGPS
pKa (Strongest Acidic)1.82ChemAxon
pKa (Strongest Basic)6.07ChemAxon
Physiological Charge-1ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count1ChemAxon
Polar Surface Area49.66 ŲChemAxon
Rotatable Bond Count1ChemAxon
Refractivity27.4 m³·mol⁻¹ChemAxon
Polarizability10.7 ųChemAxon
Number of Rings1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash KeyView
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-00mo-9000000000-8ab2bc6c045679da1664JSpectraViewer
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positivesplash10-014i-9100000000-34b6b42e5a9e4ff8715fJSpectraViewer
LC-MS/MSLC-MS/MS Spectrum - QqQ 20V, positivesplash10-014i-9000000000-97191b38aeb79930b720JSpectraViewer | MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-03dj-9700000000-f2bc2275638f96dc74acJSpectraViewer
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-014i-9100000000-72dff6639c24448bec9cJSpectraViewer
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-014l-9000000000-28eb1358005b28459debJSpectraViewer
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-03di-5900000000-0720aa91caee03b9364eJSpectraViewer
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-02t9-9400000000-cfcc87863f675fb12691JSpectraViewer
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-00kf-9000000000-a15b91c200295166bf9eJSpectraViewer
Toxicity Profile
Route of ExposureNot Available
Mechanism of ToxicityNot Available
MetabolismNot Available
Toxicity ValuesNot Available
Lethal DoseNot Available
Carcinogenicity (IARC Classification)No indication of carcinogenicity to humans (not listed by IARC).
Uses/SourcesNot Available
Minimum Risk LevelNot Available
Health EffectsChronically high levels of pyrroline-5-carboxylate are associated with at least 5 inborn errors of metabolism including: Hyperprolinemia Type I, Hyperprolinemia Type II, Iminoglycinuria, Prolinemia Type II and Pyruvate carboxylase deficiency.
SymptomsNot Available
TreatmentNot Available
Normal Concentrations
Not Available
Abnormal Concentrations
Not Available
DrugBank IDNot Available
PubChem Compound ID1196
ChEMBL IDNot Available
ChemSpider ID1159
UniProt IDNot Available
ChEBI ID1372
BioCyc IDl-delta(1)-pyrroline_5-carboxylate
CTD IDNot Available
Stitch IDNot Available
PDB IDNot Available
ACToR IDNot Available
Wikipedia Link1-pyrroline-5-carboxylate
Synthesis ReferenceNot Available
MSDSNot Available
General References
  1. Simila S: Hydroxyproline metabolism in type II hyperprolinaemia. Ann Clin Biochem. 1979 Jul;16(4):177-81. [533224 ]
  2. Mixson AJ, Phang JM: The uptake of pyrroline 5-carboxylate. Group translocation mediating the transfer of reducing-oxidizing potential. J Biol Chem. 1988 Aug 5;263(22):10720-4. [3392037 ]
  3. Wakabayashi Y: Tissue-selective expression of enzymes of arginine synthesis. Curr Opin Clin Nutr Metab Care. 1998 Jul;1(4):335-9. [10565370 ]
  4. Onenli-Mungan N, Yuksel B, Elkay M, Topaloglu AK, Baykal T, Ozer G: Type II hyperprolinemia: a case report. Turk J Pediatr. 2004 Apr-Jun;46(2):167-9. [15214748 ]
  5. Fleming GA, Hagedorn CH, Granger AS, Phang JM: Pyrroline-5-carboxylate in human plasma. Metabolism. 1984 Aug;33(8):739-42. [6748947 ]
  6. Humbertclaude V, Rivier F, Roubertie A, Echenne B, Bellet H, Vallat C, Morin D: Is hyperprolinemia type I actually a benign trait? Report of a case with severe neurologic involvement and vigabatrin intolerance. J Child Neurol. 2001 Aug;16(8):622-3. [11510941 ]
Gene Regulation
Up-Regulated GenesNot Available
Down-Regulated GenesNot Available