20S proteasome[1]

Clasto-Lactacystin β-lactone is a natural active metabolite of lactacystin, which is a metabolite of Streptomyces. Clasto-Lactacystin β-lactone is the cell cycle progression in an osteosarcoma cell line[1]. Clasto-Lactacystin β-lactone is an irreversible 20S proteasome inhibitor, and also acts as a partial inhibitor of branched amino acid preferring peptidase (BrAAP). β-Lactone inactivates approximately 60% of the BrAAP activity rapidly, and the remaining 40% of the BrAAP activity is inactivated by β-lactone at a 50-fold slower rate[2].

Researchers have developed an assay to continuously monitor the branched amino acid preferring peptidase (BrAAP) activity of the proteasome. This assay is based on the hydrolysis of the fluorogenic peptide, Abz-Gly-Pro-Ala-Leu-Ala-Nba (Abz is 2-aminobenzoyl and Nba is 4-nitrobenzylamide) which is cleaved exclusively at the Leu-Ala bond by the 20S proteasome with a kc/Km value of 13 000 M-1 s-1. Hydrolysis of this peptide is accompanied by an increase in fluorescence intensity (lambda ex = 340 nm, lambda em = 415 nm) due to release of the internally quenched 2-aminobenzoyl fluorescence that accompanies diffusion apart of the hydrolysis products, Abz-Gly-Pro-Ala-Leu and Ala-Nba. Using this assay, we examined inhibition of the BrAAP activity of the proteasome by a series of tripeptide aldehydes, Z-Leu-Leu-Xaa-H. When Xaa = Phe, (p-Cl)Phe, and Trp we observe biphasic or partial inhibition of the BrAAP activity. In contrast, when Xaa = Nva and Leu, simple inhibition kinetics are observed and allow us to calculate Ki values of 120 nM and 12 nM, respectively. The inhibitors that exhibit simple inhibition kinetics for BrAAP activity are also approximately equipotent for inhibition of the chymotrypsin-like (ChT-L) and peptidyl-glutamyl peptide hydrolyzing (PGPH) activities, dissociation constants varying by less than 25-fold, whereas the inhibitors that exhibit biphasic inhibition kinetics for BrAAP activity are >300-fold more potent for inhibiting ChT-L activity than for PGPH activity. Inactivation of the BrAAP activity of the proteasome by clasto-lactacystin beta-lactone is also biphasic. beta-Lactone inactivates approximately 60% of the BrAAP activity rapidly, with kinetics indistinguishable from its inactivation of the chymotrypsin-like activity. The remaining 40% of the BrAAP activity is inactivated by beta-lactone at a 50-fold slower rate, with kinetics indistinguishable from its inactivation of the PGPH activity. These results suggest a mechanism in which hydrolysis of Abz-Gly-Pro-Ala-Leu-Ala-Nba (i.e., BrAAP activity) occurs at two different active sites in the 20S proteasome, and that these two active sites are the same ones that catalyze the previously described ChT-L and PGPH activities [2].

[1]. A beta-lactone related to lactacystin induces neurite outgrowth in a neuroblastoma cell line and inhibits cell cycle progression in an osteosarcoma cell line. Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):3358-62.

[2]. Kinetic studies of the branched chain amino acid preferring peptidase activity of the 20S proteasome: development of a continuous assay and inhibition by tripeptide aldehydes and clasto-lactacystin beta-lactone. Biochemistry. 1998 May 26;37(21):7792-800.

Lactocytin, a naturally occurring microbial product, induces neurite growth in mouse neuroblastoma Neuro 2A cells and inhibits cell cycle progression in synchronized Neuro 2A and human osteosarcoma MG-63 cells, arresting them after the G1 phase. A related β-lactone, clastolactone β-lactone (the product of cleavagetin eliminating N-acetylcysteine), is also active, while the corresponding clastolactone dihydroxy acid is completely inactive. Lactocytin structural analogs with alterations only in the N-acetylcysteine moiety are active, while structural or stereochemical modifications to the γ-lactam ring or hydroxyisobutyl group result in partial or complete loss of activity. These inactive compounds do not antagonize the effects of lactocytin in neurite growth or cell cycle progression assays. Lactocytin-induced neurite morphology is predominantly bipolar, peaking 16–32 hours post-treatment, which is distinctly different from other treatments that induce morphological differentiation. Lactocytin-induced neurite growth appears to depend on microtubule assembly, actin polymerization, and de novo protein synthesis. The observed structure-activity relationship suggests that lactocytin and its associated β-lactones may exert their effects by acylating one or more related intracellular target molecules. [1]

C10H15NO4

213.23

213.1

C, 56.33; H, 7.09; N, 6.57; O, 30.01

154226-60-5

15283415

Colorless to light yellow liquid

1.3±0.1 g/cm3

462.9±45.0 °C at 760 mmHg

233.7±28.7 °C

0.0±2.6 mmHg at 25°C

1.534

Salinispora tropica

-1.4

2

4

2

15

327

4

C[C@@H]1[C@H]2[C@@](C(=O)O2)(NC1=O)[C@H](C(C)C)O

FWPWHHUJACGNMZ-NUMRIWBASA-N

InChI=1S/C10H15NO4/c1-4(2)6(12)10-7(15-9(10)14)5(3)8(13)11-10/h4-7,12H,1-3H3,(H,11,13)/t5-,6+,7+,10+/m1/s1

(1S,4R,5S)-1-[(1S)-1-hydroxy-2-methylpropyl]-4-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione

Omuralide clasto-Lactacystin ; A-lactone; clasto-lactacystin beta-lactone; 154226-60-5; (-)-Omuralide; (1R,4R,5S)-1-[(1S)-1-Hydroxy-2-methylpropyl]-4-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione; 6-Oxa-2-azabicyclo[3.2.0]heptane-3,7-dione, 1-[(1S)-1-hydroxy-2-methylpropyl]-4-methyl-, (1R,4R,5S)-; β-Clastolactacystin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)