E-64 HCl, the hydrochloride salt form of E-64, which is isolated from cultures of Aspergillus, is a
novel, potent, irreversible and selective cysteine protease inhibitor with IC50 of 9 nM for papain. E-64 was shown to inhibit papain, ficin and the fruit and stem bromelains, with disappearance of the thiol group of papain. E-64 has been reported to inhibit two other mammalian cysteine proteinases: cathepsin L and a proteinase from human breast-tumour tissue and the calcium-dependent proteinase, calpain, from chicken muscle. All of these characteristics suggested that E-64 might be a valuable inhibitor for the study of cysteine proteinases.
理化性质和储存条件
| Molecular Weight (MW) | 393.86 |
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| Formula | C15H28CLN5O5 |
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| CAS No. | N/A; 66701-25-5 (free base) |
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| Storage | -20℃ for 3 years in powder form |
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| -80℃ for 2 years in solvent |
| Solubility (In vitro) | DMSO: 71 mg/mL (198.7 mM) |
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| Water: <1 mg/mL |
| Ethanol: 11 mg/mL (30.8 mM) |
| SMILES Code | O=C([C@@H]1[C@@H](C(O)=O)O1)N[C@H](C(NCCCCNC(N)=N)=O)CC(C)C.[H]Cl |
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| Synonyms | E-64 HCl; E 64 HCl; E64 HCl |
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实验参考方法
| In Vitro | In vitro activity: E-64 rapidly inhibits the activities of the cysteine proteinases cathepsins B, H and L and papain, while has no effect on the serine proteinases or the metalloproteinases. E-64, as a specific inhibitor os cysteine proteases, effectively blocks in vitro ovarian cancer cell invasion. In addition, E-64 also shows antiparasitic activity against Giardia lamblia excystation in vitro. E-64 improves the preimplantation development of bovine somatic cell nuclear transfer embryos, which indicates another important implication of E-64.
Kinase Assay: The Cathepsin B activity is determined using Z-Arg-Arg-4mβNA as substrate with slight modifications. The crude extract is pre-incubated at 37°C for 5 min in 50 mM sodium acetate buffer, pH 5.0 containing 1 mM EDTA and 5 mM DTT. The substrate (final concentration, 100 μM) is added to make the final assay volume of 1 mL. The reaction mixture is incubated at 37°C for 30 min. The reaction is terminated by adding equal volume of stopping reagent containing Fast Garnet GBC salt (1 mg/mL), 10 mM pHMB and 50 mM EDTA, pH 6.0. The extraction of product, β-napthylamine (β-NA), is carried out with n-butanol. After complete layer separation, the absorbance is measured in n-butanol layer and activity is calculated using molar extinction coefficient of β-napthylamine solution as 31.5 M/cm per sec at 520 nm. One unit of enzyme activity is defined as the amount of enzyme liberating 1 μmol of βNA per minute at 37°C. The half maximal inhibitory concentration (IC50) is calculated by plotting the graph between the different concentration of E-64 and the % inhibition in cathepsin B activity. Here, IC50 indicates the concentration of the E-64 required to inhibit the parasitic cathepsin B activity by half.
Cell Assay: 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. |
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| In Vivo | E-64 induces a marked decrease in the number of spontaneous metastasis in M5076 tumor bearing mice, while has no effect on the formation of experimental metastasis. E-64 also shows antiparasitic activity against Giardia lamblia excystation in infected mice. |
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| Animal model | Wistar strain rats |
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| Formulation & Dosage | 1 mg/100 g body weight; i.p. injection |
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| References | Biopolymers. 1999;51(1):99-107; J Egypt Soc Parasitol. 2009 Apr;39(1):111-9; J Biochem. 1982 Apr;91(4):1373-80. |
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