Proline
C₅H₉NO₂·115.132 g/mol·Amino Acids·CID 145742
Amino AcidStructural
The only amino acid with a cyclic side chain bonded to the backbone nitrogen (an imino acid). Creates rigid kinks in protein chains — abundant in collagen, where every third residue is proline or hydroxyproline. Key to collagen's triple helix structure.
IUPAC: (2S)-pyrrolidine-2-carboxylic acid
Also known as: 147-85-3, proline, L-(-)-Proline, (2S)-pyrrolidine-2-carboxylic acid, (S)-Pyrrolidine-2-carboxylic acid (+14 more)
Molecular Structure
Molecular Propertiesmass · H-bonds · stereo
Molecular Weight
115.130g/mol
Exact Mass
115.063329Da
Monoisotopic Mass
115.063329Da
XLogP
-2.5
Polar Surface Area
49.3Ų
Complexity
103
Formal Charge
0
H-Bond Donors
2
H-Bond Acceptors
3
Rotatable Bonds
1
Heavy Atoms
8
Stereo Centers
1
Bond Stereo
0
Drug-Likeness (Lipinski's Rule of Five)
✓ 115.1 g/mol
MW ≤ 500
✓ -2.5
LogP ≤ 5
✓ 2
H-bond donors ≤ 5
✓ 3
H-bond acceptors ≤ 10
Passes all rules — good oral bioavailability predicted
Chemical IdentifiersSMILES · InChI
InChI
InChI=1S/C5H9NO2/c7-5(8)4-2-1-3-6-4/h4,6H,1-3H2,(H,7,8)/t4-/m0/s1
Constituent Elements
Isomers8 compounds with formula C₅H₉NO₂
pyrrolidine-2-carboxylic acid
CID 614 · 115.1 g/mol
(2R)-pyrrolidine-2-carboxylic acid
CID 8988 · 115.1 g/mol
(2S)-pyrrolidin-1-ium-2-carboxylate
CID 6971047 · 115.1 g/mol
morpholine-4-carbaldehyde
CID 20417 · 115.1 g/mol
1-aminocyclobutane-1-carboxylic acid
CID 89643 · 115.1 g/mol
methyl (Z)-3-aminobut-2-enoate
CID 643918 · 115.1 g/mol
2-aminopent-4-enoic acid
CID 14044 · 115.1 g/mol
N-(hydroxymethyl)-2-methylprop-2-enamide
CID 70208 · 115.1 g/mol