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Hydroxyproline

Athanor · official

C5H9NO3 · 131.13 g/mol

IUPAC name: (2S,4S)-4-hydroxypyrrolidine-2-carboxylic acid

Also called 4-hydroxyproline, Hyp, collagen

Amino acids
Open in Athanor
The structure of Hydroxyproline
Drawn from its SMILES with RDKit
Harmful or irritantWarningHarmful if swallowed · Harmful in contact with skin · Causes skin irritation · Causes serious eye irritation · Harmful if inhaled · May cause respiratory irritation

Names and identifiers

IUPAC name
(2S,4S)-4-hydroxypyrrolidine-2-carboxylic acid
Synonyms
4-hydroxyproline, Hyp, collagen
+ 40 more

cis-4-Hydroxy-L-proline, (4S)-4-hydroxy-L-proline, L-Proline, 4-hydroxy-, (4S)-, Hydroxyproline, cis-, L-allo-hydroxyproline, allo-4-Hydroxyproline, Hydroxyproline cis-form, 4-cis-L-hydroxyproline, cis-Hydroxyproline, Proline, 4-allo-hydroxy-, L-, allo-hydroxy-L-Proline, 43V78B6A3B, EINECS 210-542-1, CIS-L-4-HYDROXYPROLINE, NSC 206274, cis-hydroxy-L-proline, L-Proline, allo-hydroxy-, CHEBI:28397, DTXSID20883473, (2S,4S)-4-hydroxy-2-pyrrolidinecarboxylic acid, 4-HYDROXYPROLINE CIS-(-)-, cis-oxyproline, HYDROXYPROLINE CIS-FORM [MI], NSC-206274, cis-L-4-hydroxy-proline, LHydroxyproline, cis4Hydroxyproline, LAllohydroxyproline, allo4Hydroxyproline, cis4HydroxyLproline, allo4HydroxyLproline, Hydroxyproline cisform, LProline, allohydroxy, RefChem:577352, LProline, 4hydroxy, cis, (2S,4S)4Hydroxyproline, Proline, 4allohydroxy, L, LProline, 4hydroxy, (4S), LProline, 4hydroxy, cis (9CI), DTXCID301023002

Molecular formula
C5H9NO3
Empirical formula
C5H9NO3
Molecular weight
131.13 g/mol
Exact mass
131.05824
CAS number
51-35-4
PubChem CID
440015
Canonical SMILES
C1C(CNC1C(=O)O)O
Isomeric SMILES
C1[C@@H](CN[C@@H]1C(=O)O)O
InChI
InChI=1S/C5H9NO3/c7-3-1-4(5(8)9)6-2-3/h3-4,6-7H,1-2H2,(H,8,9)/t3-,4-/m0/s1
InChIKey
PMMYEEVYMWASQN-IMJSIDKUSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Calculated

Heavy atoms
9
Rings
1
Aromatic rings
0
Fraction sp³ carbons (Fsp3)
0.8
H-bond donors
3
H-bond acceptors
3 computed here · PubChem 4
Rotatable bonds
1
TPSA (Ų)
69.6
Formal charge
0
XLogP3
-3.3 PubChem
Complexity
125 PubChem
Stereocenters
2 definedCIP: C2: S · C4: S
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C45.80%
  • H6.92%
  • N10.68%
  • O36.60%

Isotope pattern

100%131.0586.0%132.061133.063

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
-1.21 Crippen (Wildman and Crippen 1999)
log S (water solubility)
0.17 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
3.31 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 131.13
  • log P ≤ 5 (Crippen): -1.21
  • H-bond donors ≤ 5: 3
  • H-bond acceptors ≤ 10: 3

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Warning

Most widely reported: 6 company reports to ECHA. Source [1].

  • Harmful or irritant
  • H302Harmful if swallowed (16.7% of reports)
  • H312Harmful in contact with skin (16.7% of reports)
  • H315Causes skin irritation (50% of reports)
  • H319Causes serious eye irritation (50% of reports)
  • H332Harmful if inhaled (16.7% of reports)
  • H335May cause respiratory irritation (50% of reports)

Precautionary statements: P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501

View all classifications (2)
  • [1] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 33.3% (2 of 6) of reports.
  • [1] European Chemicals Agency (ECHA) · 6 reports · WarningH302, H312, H315, H319, H332, H335

Safety data sheets on the supplier’s page: AChemBlock, AKos Consulting & Solutions, Alfa Chemistry.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  2. [2]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  3. [3]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  5. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  6. ·Literature on PubChem

Data last updated 2026-10-14.