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Leu-enkephalin

Athanor · official

C28H37N5O7 · 555.6 g/mol

IUPAC name: (2S)-2-[[(2S)-2-[[2-[[2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]acetyl]amino]acetyl]amino]-3-phenylpropanoyl]amino]-4-methylpentanoic acid

Also called leucine enkephalin, opioid peptide, YGGFL

Amino acidsHormones
Open in Athanor
The structure of Leu-enkephalin
Drawn from its SMILES with RDKit

Names and identifiers

IUPAC name
(2S)-2-[[(2S)-2-[[2-[[2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]acetyl]amino]acetyl]amino]-3-phenylpropanoyl]amino]-4-methylpentanoic acid
Synonyms
leucine enkephalin, opioid peptide, YGGFL
+ 35 more

[Leu]enkephalin, (Leu)enkephalin, CHEBI:89656, (2S)-2-[(2S)-2-(2-{2-[(2S)-2-AMINO-3-(4-HYDROXYPHENYL)PROPANAMIDO]ACETAMIDO}ACETAMIDO)-3-PHENYLPROPANAMIDO]-4-METHYLPENTANOIC ACID, (2S)-2-((2S)-2-(2-(2-((2S)-2-amino-3-(4-hydroxyphenyl)propanamido)acetamido)acetamido)-3-phenylpropanamido)-4-methylpentanoic acid, RefChem:1088416, 2-((2-((2-((2-((2-amino-3-(4-hydroxyphenyl)propanoyl)amino)acetyl)amino)acetyl)amino)-3-phenylpropanoyl)amino)-4-methylpentanoic acid, [Leu5]-Enkephalin, Enkephalin, Enkephalins, Enkephalin L, Tyr-Gly-Gly-Phe-Leu, Leucyl-enkephalin, Leucine-enkephalin, ENKEPHALIN, LEUCINE, H-Tyr-Gly-Gly-Phe-Leu-OH, [5-Leucine]Enkephalin, L-Tyrosylglycylglycyl-L-phenylalanyl-L-leucine, [Leu 5]enkephalin, (2S)-2-[[(2S)-2-[[2-[[2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]acetyl]amino]acetyl]amino]-3-phenylpropanoyl]amino]-4-methylpentanoic acid, MFCD00076406, Tyr-Gly-Gly-Phe-Leu-OH, L-Tyr-Gly-Gly-L-Phe-L-Leu, RI01R707R6, C28H37N5O7, N-(N-(N-(N-L-Tyrosylglycyl)glycyl)-L-phenylalanyl)-L-leucine, Leu-enkephalin;Leucine enkephalin;Leucyl-enkephalin, L-Leucine, N-(N-(N-(N-L-tyrosylglycyl)glycyl)-L-phenylalanyl)-, Dynorphin-(1-5), SH-PENTAPEPTIDE-5, UNII-RI01R707R6, TyrGlyGlyPheLeu, CCRIS 6338, NSC350588, Leu5-Enkephalin

Molecular formula
C28H37N5O7
Empirical formula
C28H37N5O7
Molecular weight
555.6 g/mol
Exact mass
555.26930
CAS number
58822-25-6
PubChem CID
461776
Canonical SMILES
CC(C)CC(C(=O)O)NC(=O)C(CC1=CC=CC=C1)NC(=O)CNC(=O)CNC(=O)C(CC2=CC=C(C=C2)O)N
Isomeric SMILES
CC(C)C[C@@H](C(=O)O)NC(=O)[C@H](CC1=CC=CC=C1)NC(=O)CNC(=O)CNC(=O)[C@H](CC2=CC=C(C=C2)O)N
InChI
InChI=1S/C28H37N5O7/c1-17(2)12-23(28(39)40)33-27(38)22(14-18-6-4-3-5-7-18)32-25(36)16-30-24(35)15-31-26(37)21(29)13-19-8-10-20(34)11-9-19/h3-11,17,21-23,34H,12-16,29H2,1-2H3,(H,30,35)(H,31,37)(H,32,36)(H,33,38)(H,39,40)/t21-,22-,23-/m0/s1
InChIKey
URLZCHNOLZSCCA-VABKMULXSA-N
Molfile

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

Calculated

Heavy atoms
40
Rings
2
Aromatic rings
2
Fraction sp³ carbons (Fsp3)
0.39
H-bond donors
7
H-bond acceptors
7 computed here · PubChem 8
Rotatable bonds
15
TPSA (Ų)
199.9 computed here · PubChem 200
Formal charge
0
XLogP3
-2.3 PubChem
Complexity
854 PubChem
Stereocenters
3 definedCIP: C2: S · C22: S · C33: 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

  • C60.53%
  • H6.71%
  • N12.60%
  • O20.16%

Isotope pattern

100%555.26933%556.2726.7%557.2751.0%558.278559.280

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
-0.16 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-2.41 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
3.29 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 555.63
  • log P ≤ 5 (Crippen): -0.16
  • H-bond donors ≤ 5: 7
  • H-bond acceptors ≤ 10: 7

Breaks 2 of the 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

No GHS hazard classification was found in the sources.

Safety data sheets on the supplier’s page: Glixx Labs Inc, AA BLOCKS, SynHet - Synthetic Heterocycles.

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

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  2. ·Literature on PubChem

Data last updated 2026-10-14.