Article · Wikipedia archive · Last revised Jun 26, 2026

Leupeptin

Leupeptin, also known as N-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases.

Last revised
Jun 26, 2026
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≈ 2 min
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525 w
Citations
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Source
Wikipedia ↗
Leupeptin
Stereo, skeletal formula of leupeptin
Stereo, skeletal formula of leupeptin source ↗
Names
IUPAC name
N-Acetyl-leucyl-N-{[5-[(diaminomethylidene)amino]-1-oxopentan-2-yl}-leucinamide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.212.237
UNII
  • 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 checkY
    Key: GDBQQVLCIARPGH-ULQDDVLXSA-N checkY
  • 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
Properties
C20H38N6O4
Molar mass 426.562 g·mol−1
Related compounds
Related alkanamides
 Gusperimus
Related compounds
 Synthalin
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Leupeptin, also known as N-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases.

It is often used during in vitro experiments when a specific enzymatic reaction is being studied. When cells are lysed for these studies, proteases, many of which are contained within lysosomes, are released. These proteases, if freely present in the lysate, would destroy any products from the reaction being studied, and make the experiment uninterpretable. For example, leupeptin could be used in a calpain extraction to keep calpain from being hydrolyzed by specific proteases. The suggested concentration is 1-10 μM (0.5-5 μg/ml).

Leupeptin is an organic compound produced by actinomycetes, which inhibits serine, cysteine and threonine proteases. Leupeptin inhibits serine proteinases (trypsin (Ki=3.5 nM), plasmin (Ki= 3.4 nM), porcine kallikrein), and cysteine proteinases (papain, cathepsin B (Ki = 4.1 nM), endoproteinase Lys-C). It does not inhibit α-chymotrypsin or thrombin. Leupeptin is a competitive transition state inhibitor and its inhibition may be relieved by an excess of substrate.

Leupeptin is soluble in water (stable for 1 week at 4 °C and 1 month at −20 °C), ethanol, acetic acid and DMF.

It can be given topically for middle and inner ear infections.1

Crystal structure of Leupeptin (silver) in the Trypsin (green) binding pocket.
Crystal structure of Leupeptin (silver) in the Trypsin (green) binding pocket. Hydrogen bonds are shown as yellow dotted lines. Rendered from PDB 1JRS. source ↗

Biosynthesis

The biosyntheis of leupeptin in a Streptomyces species has been studied. It is a tripeptide and its synthesis from its component amino acids begins when L-leucine is converted to levacetylleucine by the enzyme leucine N-acetyltransferase.2

2D representation of the chemical structure of leucine .
leucine
+
 
acetyl-CoA
 
 
 
Reversible left-right reaction arrow
 
 
 
2D representation of the chemical structure of levacetylleucine .
levacetylleucine
+
 
+ coenzyme A
 


The next steps are the addition of a second L-leucine fragment, adding an amide bond, followed by L-arginine, giving leupeptin acid. In the final step, the acid terminus from the arginine is reduced to its aldehyde.345

References

References

  1. "11 Applications for Leupeptin, Hemisulfate | AG Scientific Blog".
  2. Suzukake, Kayoko; Hayashi, Hidemi; Hori, Makoto; Umezawa, Hamao (1980). "Biosynthesis of leupeptin. III. Isolation and properties of an enzyme synthesizing acetyl-L-leucine". The Journal of Antibiotics. 33 (8): 857–862. doi:10.7164/antibiotics.33.857. PMID 7429989.
  3. Hori, Makoto; Hemmi, Hiromichi; Suzukake, Kayoko; Hayashi, Hidemi; Uehara, Yoshimasa; Takeuchi, Tomio; Umezawa, Hamao (1978). "Biosynthesis of leupeptin". The Journal of Antibiotics. 31 (1): 95–98. doi:10.7164/antibiotics.31.95. PMID 627527.
  4. Suzukake, Kayoko; Fujiyama, Takao; Hayashi, Hidemi; Hori, Makoto; Umezawa, Hamao (1979). "Biosynthesis of leupeptin. II. Purification and properties of leupeptin acid synthetase". The Journal of Antibiotics. 32 (5): 523–530. doi:10.7164/antibiotics.32.523. PMID 43319.
  5. Suzukake, Kayoko; Takada, Masahiko; Hori, Makoto; Umezawa, Hamao (1980). "Biosynthesis of leupeptin IV. Is protein turnover in leupeptin producer cells affected by leupeptin?". The Journal of Antibiotics. 33 (10): 1172–1176. doi:10.7164/antibiotics.33.1172. PMID 7451369.