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Catalog No.: GC13418

A fungal metabolite with diverse biological activities

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E-64 Chemical Structure

Cas No.:66701-25-5

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10mM (in 1mL DMSO)
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Sample solution is provided at 25 µL, 10mM.

Product Documents

Quality Control & SDS

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Cell experiment: [1]

Cell lines

H-59 and M-27 cells

Preparation method

The solubility of this compound in DMSO is ≥53.6mg/mL. General tips for obtaining a higher concentration: Please warm the tube at 37 °C for 10 minutes and/or shake it in the ultrasonic bath for a while.Stock solution can be stored below -20°C for several months.

Reaction Conditions

10 μg/ml , 48 hours


E-64 inhibited H-59 invasion in a dose-dependent manner with a maximal inhibition of 97% at a concentration of 10 μg/ml which was non-toxic. Cell migration as measured with filters coated with 7.5 μg/filter type IV collagen was reduced by only 25% suggesting that the cysteine proteinases played a more minor role in cell migration in the absence of a basement membrane barrier. On the other hand M-27 invasion was not significantly affected by treatment with E-64 even at concentrations as high as 100 μg/ml.

Animal experiment: [2]

Animal models

Wistar strain rats

Dosage form

Intraperitoneal injection, 1 mg/100 g body weight


The animals were killed 1 h after the injection and the cathepsin B and cathepsin L activities in the lysosomal were assayed. The inhibition caused by E-64 was already detectable 1 hour after its injection.

Other notes

Please test the solubility of all compounds indoor, and the actual solubility may slightly differ with the theoretical value. This is caused by an experimental system error and it is normal.


[1] Navab R, Mort J S, Brodt P. Inhibition of carcinoma cell invasion and liver metastases formation by the cysteine proteinase inhibitor E-64. Clinical & experimental metastasis, 1997, 15(2): 121-129.

[2] Hashida S, TOWATARI T, KOMINAMI E, et al. Inhibitions by E-64 derivatives of rat liver cathepsin B and cathepsin L in vitro and in vivo. Journal of biochemistry, 1980, 88(6): 1805-1811.


A new class of compounds that show promise of acting as class-specific inhibitors for the cysteine proteinases are the L-trans-epoxysuccinylpeptides related to the compound E-64 [L-trans-epoxysuccinyl-L-leucylamido(4-guanidino)butanel , isolated from cultures of Aspergillus. E-64 was shown to inhibit papain, ficin and the fruit and stem bromelains, with disappearance of the thiol group of papain1.

 E-64 has been reported to inhibit two other mammalian cysteine proteinases: cathepsin L3 and a proteinase from human breast-tumour tissue4 and the calcium-dependent proteinase, calpain, from chicken muscle5. All of these characteristics suggested that E-64 might be a valuable inhibitor for the study of cysteine proteinases.

Lineweaver-Burk plots of inhibition data show that the action of E-64 was not competitive with substrate1 . Moreover, the optical isomerism of the epoxysuccinyl moiety seemed to have no effect on the activity of E-64 as an inhibitor of papain6, 7 .If E-64 were indeed acting by covalent reaction at the active site, its rate of reaction would be decreased by the presence of leupeptin, a tight-binding reversible inhibitor8.

E-64 inhibits only cysteine proteinases. Papain showed a particularly high reactivity with E-64, and good rates were also obtained with the other plant enzymes and the lysosomal cysteine proteinases. There is structural evidence that these enzymes form a homologous group9, and they resemble each other in having Mr about 25 000, no (detected) zymogens and no distinct requirement for calcium. Chicken skeletal-muscle calpain is reported to be inhibited by E-64, but the rate constant has not been determined5.

The most obvious practical application of E-64 is in the active-site titration of the papain-related cysteine proteinases. Active-site titration as a method of determining enzyme concentration has the advantage over rate assays of being insensitive to reaction conditions, and giving a result in active-site molarity10 (Bender et al., 1966).

1. A. J. BARRETT, A. A. KEMBHAVI, L-trans-Epoxysuccinyl-leucylamido(4-guanidino)butane (E-64) and its analogues as inhibitors of cysteine proteinases including cathepsins B, H and L. Biochem. J. (1982) 201, 189-198
2. Hanada, K., Tamai, M., Yamagishi, M., Ohmura, S., Sawada, J. & Tanaka, I. (1978c) Agric. Biol. Chem. 42, 523-528
3. Towatari, T., Tanaka, K., Yoshikawa, D. & Katunuma, N. (1978).J. Biochem. (Tokyo) 84, 659-671.
4. Mort, J. S., Recklies, A. D. & Poole, A. R. (1980) Biochim. Biophys. Acta 614, 134-143.
5. Sugita, H., Ishiura, S., Suzuki, K. & Imahori, K. (1980) J. Biochem. (Tokyo) 87, 339-341
6. Hanada, K., Tamai, M., Morimoto, S., Adachi, T.,Ohmura, S., Sawada, J. & Tanaka, I. (1978a) Agric. Biol. Chem. 42, 537-541.
7. Hanada, K., Tamai, M., Ohmura, S., Sawada, J., Seki, T.& Tanaka, I. (1978b)Agric. Biol. Chem. 42, 529-536
8. Knight, C. G. (1980) Biochem. J. 189,447-453
9. Takio, K., Towatari, T., Katunuma, N. & Titani, K.(1980) Biochem. Biophys. Res. Commun. 97, 340-346
10. Bender, M. L., Begue-Canton, M. L., Blakeley, R. L.,Brubacher, L. J., Feder, J., Gunter, C. R., Kezdy, F. J.,Killheffer, J. V., Marshall, T. H., Miller, C. G., Roeske,R. W. & Stoops, J. K. (1966) J. Am. Chem. Soc. 88,5890-5913

Chemical Properties

Cas No. 66701-25-5 SDF
Chemical Name (2S,3S)-3-[[(2S)-1-[4-(diaminomethylideneamino)butylamino]-4-methyl-1-oxopentan-2-yl]carbamoyl]oxirane-2-carboxylic acid
Formula C15H27N5O5 M.Wt 357.41
Solubility ≥ 53.6mg/mL in DMSO Storage Store at 2-8°C
General tips For obtaining a higher solubility , please warm the tube at 37 ℃ and shake it in the ultrasonic bath for a while.Stock solution can be stored below -20℃ for several months.
Shipping Condition Evaluation sample solution : ship with blue ice
All other available size: ship with RT , or blue ice upon request

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Research Update

Effect of E-64 Supplementation during In Vitro Maturation on the Developmental Competence of Bovine OPU-Derived Oocytes

Genes (Basel) 2022 Feb 10;13(2):324.35205369 PMC8872247

Recovery of bovine oocytes using the ovum pick-up (OPU) technique offers the advantage of rapid genetic improvement through propagation of desired genes from animals with high genetic qualities. However, the developmental competence of OPU-derived immature oocytes remains relatively poor. We previously found that cathepsin B gene expression and activity are increased in poor quality oocytes and embryos compared to good quality ones. In this study, we investigated the effect of E-64 (cathepsin B inhibitor) supplementation during in vitro maturation (IVM) on the developmental competence of OPU-derived immature oocytes and the quality of the produced blastocysts. Our results showed that supplementation of IVM medium with E-64 significantly improved the developmental competence of OPU-derived immature oocytes as evidenced by the significant increase of the blastocyst rate. Importantly, the presence of E-64 during IVM also significantly improved blastocyst quality by increasing the total cell number and decreasing the percentage of TUNEL positive cells. These results indicate that E-64 supplementation during IVM is a promising tool to improve the efficiency of OPU-IVF program by improving the developmental competence of OPU-derived immature oocytes.

Small molecule inhibitor E-64 exhibiting the activity against African swine fever virus pS273R

Bioorg Med Chem 2021 Apr 1;35:116055.33607487 10.1016/j.bmc.2021.116055

African swine fever (ASF) is a viral disease in swine that results in high mortality in domestic pigs and causes considerable economic losses. Currently, there is no effective vaccine or drugs available for treatment. Identification of new anti-ASFV drugs is urgently needed. Here, the pS273R protein of the African swine fever virus (ASFV) is a specific SUMO-1-like cysteine protease that plays an important role in its replication process. To inhibit virus replication and improve treatment options, a set of small-molecule compounds, targeted inhibitors against the ASFV pS273R protease, were obtained through molecular screening by homology modeling and molecular docking based on structural information of pS273R. Our results clearly demonstrated that the 14th carbon atom of the cysteinase inhibitor E-64 could form one CS covalent bond with the Cys 232 amino acid of the pS273R protease and seven additional hydrogen bonds to maintain a stable binding state. Simultaneously, cell viability, immunophenotyping, and in vitro enzyme activity inhibition assays were performed to comprehensively evaluate E-64 characteristics. Our findings demonstrated that 4 mmol/L E-64 could effectively inhibit the enzyme activity center of the pS273R protease by preventing pS273R protease from lysing pp62, while promoting the upregulation of immune-related cytokines at the transcription level. Moreover, cell viability results revealed that 4 mmol/L E-64 was not cytotoxic. Taken together, we identified a novel strategy to potentially prevent ASFV infection in pigs by blocking the activity of pS273R protease with a small-molecule inhibitor.

Chronic cathepsin inhibition by E-64 in Dahl salt-sensitive rats

Physiol Rep 2016 Sep;4(17):e12950.27597769 PMC5027357

Cysteine cathepsins are lysosomal enzymes expressed in the kidneys and other tissues, and are involved in the maturation and breakdown of cellular proteins. They have been shown to be integrally involved in the progression of many cardiovascular and renal diseases. The goal of this study was to determine the involvement of cysteine cathepsins in the development of salt-sensitive hypertension and associated kidney damage. In our experiments, Dahl salt-sensitive (SS) rats were fed an 8% high salt NaCl diet and intravenously infused with the irreversible cysteine cathepsin inhibitor E-64 (1 mg/day) or the vehicle (control). Both the control and E-64 infused groups developed significant hypertension and kidney damage, and no difference of the mean arterial pressure and the hypertension-associated albuminuria was observed between the groups. We next tested basal calcium levels in the podocytes of both control and infused groups using confocal calcium imaging. Basal calcium did not differ between the groups, indicative of the lack of a protective or aggravating influence by the cathepsin inhibition. The efficacy of E-64 was tested in Western blotting. Our findings corresponded to the previously reported, E-64 induced increase in cathepsin B and L abundance. We conclude that the inhibition of cysteine cathepsins by E-64 does not have any effects on the blood pressure development and kidney damage, at least under the studied conditions of this model of SS hypertension.

Crystal structure of an actinidin-E-64 complex

Biochemistry 1992 Jun 9;31(22):5172-6.1606141 10.1021/bi00137a012

E-64, 1-(L-trans-epoxysuccinylleucylamino)-4-guanidinobutane, is a potent and highly selective irreversible inhibitor of cysteine proteases. The crystal structure of a complex of actinidin and E-64 has been determined at 1.86-A resolution by using the difference Fourier method and refined to an R-factor of 14.5%. The electron density map clearly shows that the C2 atom of the E-64 epoxide ring is covalently bonded to the S atom of the active-site cysteine 25. The charged carboxyl group of E-64 forms four H-bonds with the protein and thus may play an important role in favorably positioning the inhibitor molecule for nucleophilic attack by the active-site thiolate anion. The interaction features between E-64 and actinidin are very similar to those seen in the papain-E-64 complex; however, the amino-4-guanidinobutane group orients differently. The crystals of the actinidin-E-64 complex diffracted much better than the papain-E-64 complex, and consequently the present study provides more precise geometrical information on the binding of the inhibitor. Moreover, this study provides yet another confirmation that the binding of E-64 is at the S subsites and not at the S' subsites as has been previously proposed. The original actinidin structure has been revised using the new cDNA sequence information.

Inhibitions by E-64 derivatives of rat liver cathepsin B and cathepsin L in vitro and in vivo

J Biochem 1980 Dec;88(6):1805-11.7462205 10.1093/oxfordjournals.jbchem.a133155

The mechanism of inhibition of cathepsin B [EC] and cathepsin L [EC 3.4.22.-] by E-64 was investigated. Kinetic studies indicated that E-64 was an irreversible inhibitor of these enzymes. [3H]E-64 is incorporated into cathepsin B in a one/one molar ratio in parallel with inactivation of the enzyme. Titration of one of the 10 SH groups of native cathepsin B with 2,2'-dithiodipyridine resulted in complete loss of enzyme activity. Decrease of titratable SH groups and activity of cathepsin B was proportional to the concentration of E-64 added, indicating that E-64 binds to an equimolar amount of active SH residues of cathepsin B. The effects of E-64 and its derivatives on lysosomal cathepsin B and cathepsin L in rat liver were studied in vitro and in vivo. The D form of E-64 inhibited the cathepsin both in vitro and in vivo, although its inhibitory effects were less than those of E-64-(L). E-64-b(RR), in which the terminal agmatine of E-64 is replaced by leucine, was as active as E-64-(L) in vitro, but was completely inactive in vivo. Among the E-64 derivatives tested, E-64-c(SS), in which the terminal agmatine of E-64 is replaced by isoarylamide, showed strong inhibitory activity in vivo, like E-64-(L).


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