L2884 Sigma-Aldrich


microbial, ≥90% (HPLC)

Synonym: Acetyl-Leu-Leu-Arg-al, Leupeptin hemisulfate salt, N-Acetyl-L-leucyl-L-leucyl-L-argininal hemisulfate salt

  • CAS Number 103476-89-7

  • Linear Formula C20H38N6O4 · 1/2H2SO4

  • Molecular Weight 475.59

  •  MDL number MFCD00037012

  •  PubChem Substance ID 24896328

  •  NACRES NA.77



Related Categories Biochemicals and Reagents, Broad Spectrum Inhibitors of Proteolytic Enzyme Classes, Cell Biology, Cell Signaling and Neuroscience, Core Bioreagents,
Quality Level   300
biological source   microbial
assay   ≥90% (HPLC)
form   powder
solubility   H2O: 10 mM (Solutions are stable for a week at 4 °C. Stock solutions are stable up to 6 months at −20 °C.)
  H2O: 50 mg/mL
storage temp.   −20°C
SMILES string   OS(O)(=O)=O.CC(C)C[C@H](NC(C)=O)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCNC(N)=N)C=O.CC(C)C[C@H](NC(C)=O)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCNC(N)=N)C=O
InChI   1S/2C20H38N6O4.H2O4S/c2*1-12(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;1-5(2,3)4/h2*11-13,15-17H,6-10H2,1-5H3,(H,24,28)(H,25,29)(H,26,30)(H4,21,22,23);(H2,1,2,3,4)/t2*15-,16-,17-;/m00./s1


General description

Leupeptin, or N-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring tripeptide that acts particularly as a serine protease inhibitor and as a cysteine protease inhibitor. Its mechanism of action involves structurally similar covalent binding reactions:
• In the active site of serine proteases, leupeptin forms a covalent hemiacetal adduct between the aldehyde group of leupeptin and the hydroxyl group of a serine residue in the enzyme active site.
• In the active site of cysteine proteases, the electrophilic (aldehyde) carbon of leupeptin forms a comparable bond with the sulfur atom of a cysteine residue in the enzyme active site.


5, 10, 25, 50, 100, 250 mg in glass bottle

Biochem/physiol Actions

Inhibitor of serine and cysteine proteases. Inhibits plasmin, trypsin, papain, calpain, and cathepsin B. Does not inhibit pepsin, cathepsins A and D, thrombin, or α-chymotrypsin. Effective concentration 10-100 μM. There have been numerous studies using leupeptin to protect against hearing loss caused by acoustic overstimulation or the ototoxic antibiotic gentamicin. (Loss of cochlear hair cells is believed to be mediated by calpain.)

Analysis Note

Leupeptin gives multiple peaks on HPLC due to equilibria among three forms in solution. Purity determined using three main peaks. Majority of contaminating peptide is racemized leupeptin.

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Protocols & Articles


Roar Assay Kits for Studies in Lipoprotein Metabolism

This technical article is a compilation of select fluorescence-based activity assays developed by Roar Biomedical now offered through Sigma-Aldrich in kit format. The methods are well-characterized, ...
Robert Brocia
Roar Biomedical, Inc.
Keywords: Addition reactions, Cardiovascular, Chromatography, Clinical, Detection methods, Drug discovery, Esterifications, Gas chromatography, High performance liquid chromatography, Separation, Thin layer chromatography


MTP Activity Assay Kit Protocol

The kit is sufficient for 100 assays in 200 µL total assay volume. Donor Particle                                0.4 mL     Catalog Number MAK110A Acceptor Particle                            0.4 mL ...
Keywords: Buffers, Homogenization, Sample preparations

Peer-Reviewed Papers


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