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Leupeptin

Athanor · official

C20H38N6O4 · 426.6 g/mol

IUPAC name: (2S)-2-acetamido-N-[(2S)-1-[[(2S)-5-(diaminomethylideneamino)-1-oxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]-4-methylpentanamide

Also called N-acetyl-Leu-Leu-argininal, protease inhibitor, serine protease inhibitor

ReagentsAmino acids
Open in Athanor
The structure of Leupeptin
Drawn from its SMILES with RDKit
Harmful or irritantWarningHarmful if swallowed · Harmful if inhaled

Names and identifiers

IUPAC name
(2S)-2-acetamido-N-[(2S)-1-[[(2S)-5-(diaminomethylideneamino)-1-oxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]-4-methylpentanamide
Synonyms
N-acetyl-Leu-Leu-argininal, protease inhibitor, serine protease inhibitor
+ 36 more

CHEBI:6426, J97339NR3V, acetyl-l-leucyl-l-leucyl-l-argininal, (2S)-2-acetamido-N-[(2S)-1-[[(2S)-5-(diaminomethylideneamino)-1-oxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]-4-methylpentanamide, N-Acetyl-L-leucyl-L-leucyl-L-argininal, DTXSID1020776, L-LEUCINAMIDE, N-ACETYL-L-LEUCYL-N-((1S)-4-((AMINOIMINOMETHYL)AMINO)-1-FORMYLBUTYL)-, L-LEUCINAMIDE, N-ACETYL-L-LEUCYL-N-(4-((AMINOIMINOMETHYL)AMINO)-1-FORMYLBUTYL)-, (S)-, L-Leucinamide, N-acetyl-L-leucyl-N-[(1S)-4-[(aminoiminomethyl)amino]-1-formylbutyl]-, (2S)-2-acetamido-N-((2S)-1-(((2S)-5-(diaminomethylideneamino)-1-oxopentan-2-yl)amino)-4-methyl-1-oxopentan-2-yl)-4-methylpentanamide, RefChem:799002, DTXCID90776, 600-443-5, 640-991-2, 686-481-3, Ac-Leu-Leu-Arg-H, Acetyl-L-leucyl-L-leucylargininal, C20H38N6O4, Leupeptin (hemisulfate), Ac-LLR-H, LEUPEPTINS [MI], BSPBio_001195, KBioGR_000535, KBioSS_000535, N-acetyl-leucylleucylargininal, Ac-L-Leu-L-Leu-L-Arg-H, SCHEMBL583830, UNII-J97339NR3V, CHEMBL191881, SCHEMBL4458973, SCHEMBL10378726, KBio2_000535, KBio2_003103, KBio2_005671, KBio3_000969, KBio3_000970

Molecular formula
C20H38N6O4
Empirical formula
C10H19N3O2
Molecular weight
426.6 g/mol
Exact mass
426.29545
CAS number
103476-89-7
PubChem CID
72429
Canonical SMILES
CC(C)CC(C(=O)NC(CC(C)C)C(=O)NC(CCCN=C(N)N)C=O)NC(=O)C
Isomeric SMILES
CC(C)C[C@@H](C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCN=C(N)N)C=O)NC(=O)C
InChI
InChI=1S/C20H38N6O4/c1-12(2)9-16(24-14(5)28)19(30)26-17(10-13(3)4)18(29)25-15(11-27)7-6-8-23-20(21)22/h11-13,15-17H,6-10H2,1-5H3,(H,24,28)(H,25,29)(H,26,30)(H4,21,22,23)/t15-,16-,17-/m0/s1
InChIKey
GDBQQVLCIARPGH-ULQDDVLXSA-N
Molfile

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

Calculated

Heavy atoms
30
Rings
0
Aromatic rings
0
Fraction sp³ carbons (Fsp3)
0.75
H-bond donors
6 computed here · PubChem 5
H-bond acceptors
5
Rotatable bonds
14
TPSA (Ų)
166.3 computed here · PubChem 169
Formal charge
0
XLogP3
0.4 PubChem
Complexity
602 PubChem
Stereocenters
3 definedCIP: C5: S · C13: S · C21: 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

  • C56.32%
  • H8.98%
  • N19.70%
  • O15.00%

Isotope pattern

100%426.29624%427.2983.7%428.301429.303

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
0.02 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-1.57 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
3.54 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 426.56
  • log P ≤ 5 (Crippen): 0.02
  • H-bond donors ≤ 5: 6
  • H-bond acceptors ≤ 10: 5

Breaks 1 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

Warning

Most widely reported: 7 company reports to ECHA. Source [1].

  • Harmful or irritant
  • H302Harmful if swallowed
  • H332Harmful if inhaled (14.3% of reports)

Precautionary statements: P261, P264, P270, P271, P301+P317, P304+P340, P317, P330, P501

View all classifications (4)
  • [1] European Chemicals Agency (ECHA) · 7 reports · WarningH302, H332
  • [1] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 20% (1 of 5) of reports.
  • [1] European Chemicals Agency (ECHA) · 5 reports · WarningH302, H312, H332, H361
  • [1] European Chemicals Agency (ECHA) · 2 reports · WarningH302, H312, H332, H341

Safety data sheets on the supplier’s page: eMolecules, Mcule, BLD Pharm.

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]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  3. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  4. ·Literature on PubChem

Data last updated 2026-10-14.