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| 1mg |
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| Targets |
Opioid receptors (primarily delta and micro). Leu-enkephalin (Tyr-Gly-Gly-Phe-Leu) is an endogenous opioid pentapeptide that acts as an agonist at delta and micro opioid receptors with preference for delta. N-terminal acetylation blocks the free amine, which is critical for high-affinity receptor binding; thus, this derivative may have reduced binding affinity and altered pharmacological activity.
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| ln Vitro |
The spinal dorsal horn contains two kinds of opioid peptides: dynorphins and enkephalins (met-, leu-, and enkephalin 8). The three main opioid receptor subtypes are mu, delta, and kappa. Potential endogenous ligands for delta opioid receptors include enkephalins, while endogenous ligands for kappa opioid receptors are dynorphins. Three receptor types that bear resemblance to the δ- and κ-type opioid receptors seen in vertebrates have been identified pharmacologically in nervous tissues (e.g., Ki=18.9 nM for Leu-enkephalin), and they have been localized at the CHH terminals in the SG of C by autoradiography. maenas [1].
Specific in vitro binding data (IC50 or Ki values) are not reported for this acetylated derivative. Acetylation of the N-terminal tyrosine amino group is known to significantly reduce or abolish binding affinity at opioid receptors because the free N-terminus is essential for opioid receptor recognition and activation. Therefore, this compound likely has very low (or negligible) activity as an opioid agonist and may serve as a negative control or metabolic standard in opioid research. |
| ln Vivo |
No specific in vivo activity data are reported for this compound. Acetylation of the N-terminus prevents recognition by the N-terminal binding pocket of opioid receptors, so this compound is not expected to produce significant analgesic or other opioid-mediated effects in vivo. It is likely an inactive analogue and may be used as a control or for metabolic stability studies. Its Leu-enkephalin core may be recognized by peptidases but not by opioid receptors.
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| Enzyme Assay |
N-terminally acetylated Leu-enkephalin is not suitable for standard radioligand binding assays because it lacks significant affinity for opioid receptors. It may be used as a negative control to demonstrate specificity of receptor binding. In standard protocols, membranes from CHO cells expressing micro, delta, or kappa receptors are incubated with radioligands (e.g., [3H]-DAMGO for micro, [3H]-DPDPE for delta) and increasing concentrations of unlabeled peptide, including this acetylated derivative. No significant displacement of radioligand is expected (IC50 > 10 uM). In mass spectrometry-based binding assays, the compound may serve as an internal standard.
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| Cell Assay |
Cell-based functional assays (e.g., cAMP accumulation inhibition, calcium mobilization) in cells expressing micro, delta, or kappa opioid receptors can be performed. Cells are treated with N-terminally acetylated Leu-enkephalin at concentrations up to 10-100 uM, and no significant agonist activity (i.e., no inhibition of forskolin-stimulated cAMP accumulation, no calcium flux) is expected. The compound may be used as a negative control to confirm that the effects of Leu-enkephalin or other opioid peptides are receptor-specific. It may also be used in peptidase stability assays to compare degradation rates with the native peptide.
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| Animal Protocol |
No specific in vivo animal protocols are published for this compound. If used as a control, it would be administered i.c.v. or i.p. to mice or rats at doses equivalent to those used for Leu-enkephalin (e.g., 10-100 ug i.c.v.). No analgesic response (tail-flick latency increase) would be observed, confirming the necessity of the free N-terminus for opioid receptor activation. For peptidase stability studies, it would be administered i.v., and plasma or brain samples would be collected for LC-MS/MS analysis to measure the half-life of the acetylated peptide compared to Leu-enkephalin. Acetylation may confer resistance to aminopeptidase degradation, resulting in a longer plasma half-life.
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| ADME/Pharmacokinetics |
No specific pharmacokinetic data are reported for this acetylated peptide. The molecular formula is C30H39N5O8 with molecular weight 597.66. CAS# 2703746-32-9. Sequence: Ac-L-Tyr-Gly-Gly-L-Phe-D-Leu-COOH. Solubility: water (10-50 mg/mL). Storage: -20degC, dry, protected from light. N-terminal acetylation is likely to increase resistance to aminopeptidase degradation in the blood and tissues, potentially increasing plasma half-life compared to native Leu-enkephalin. However, the peptide may still be degraded by other peptidases (e.g., neutral endopeptidase). Penetration of the BBB is expected to be very low, similar to other opioid peptides.
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| Toxicity/Toxicokinetics |
No toxicity data are reported for this compound. At concentrations used in research (nM to uM in vitro, mg/kg in vivo), no significant toxicity is expected. As an acetylated endogenous peptide derivative, it is likely to be well-tolerated. The TFA salt form contains trifluoroacetate, which may be toxic at high concentrations, but at experimental concentrations, it is generally considered safe. No FDA approval. For research use only.
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| References | |
| Additional Infomation |
Other information: N-terminally acetylated Leu-enkephalin (CAS# 2703746-32-9) is a research-grade peptide, not FDA-approved. Purity ≥98%. It is the N-terminally acetylated derivative of the endogenous opioid pentapeptide Leu-enkephalin (Tyr-Gly-Gly-Phe-Leu). N-terminal acetylation blocks the free amine required for high-affinity opioid receptor binding, rendering it inactive as an agonist. It may be used as a negative control, a metabolic standard, or for studying the structure-activity relationship (SAR) of opioid peptides. For research use only.
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| CAS # |
2703746-32-9
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| Appearance |
White to off-white solid powder
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
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
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| Solubility (In Vivo) |
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.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *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). View More
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)] Oral Formulations
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). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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