Mastoparan 17 does not have a defined biological target because it is an inactive analog. It is designed to be inactive at G proteins (such as Gi/o) and does not induce mast cell degranulation or other cellular responses typically associated with mastoparan. The original mastoparan is known to activate heterotrimeric G proteins (especially Gi and Go) by mimicking the function of a G protein-coupled receptor (GPCR) or by directly stimulating nucleotide exchange, leading to the activation of downstream effectors such as phospholipase C (PLC) and the release of intracellular calcium. Mastoparan 17 lacks this activity, likely due to the substitution that disrupts the amphipathic alpha-helical structure or its ability to interact with the G protein. Therefore, Mastoparan 17 is used as a negative control to ensure that the biological effects observed with active mastoparan peptides are due to specific G protein activation and not to non-specific membrane perturbation or other off-target effects.

In vitro studies demonstrate that Mastoparan 17 is a tetradecapeptide that is an inactive analog of mastoparan. It does not induce the biological activities associated with the native mastoparan peptide, such as G protein activation, phospholipase C (PLC) activation, calcium mobilization, or mast cell degranulation. It is used as a negative control in cell-based and biochemical assays to verify the specificity of results obtained with active mastoparan peptides. For example, in a GTPgammaS binding assay using purified Gi or Go proteins, mastoparan (1-10 uM) stimulates the binding of 35S-GTPgammaS, whereas Mastoparan 17 at the same concentrations does not. In a calcium mobilization assay in HL-60 cells or other cell lines, mastoparan induces a rapid increase in intracellular calcium (measured by Fluo-4 or Fura-2 fluorescence), while Mastoparan 17 does not. In a mast cell degranulation assay (e.g., RBL-2H3 cells), mastoparan causes the release of beta-hexosaminidase, a marker of degranulation, whereas Mastoparan 17 does not. In plant cell studies, mastoparan-induced Ca2+ fluxes may regulate cell-to-cell communication, whereas Mastoparan 17 is used as a control. The lack of activity of Mastoparan 17 confirms that the effects of the active peptide are not due to non-specific membrane perturbation or detergent-like activity, but rather to specific interactions with G proteins or other targets.

In vivo activity data for Mastoparan 17 is not available, as it is an inactive analog used as a negative control. It is not intended for therapeutic use and has not been evaluated in animal models for pharmacological effects. It may be used in vivo in a research setting as a control for the active mastoparan peptide. For example, if mastoparan (e.g., 1-10 mg/kg) is administered intraperitoneally (i.p.) to mice and causes a biological effect (e.g., hypotension, increased vascular permeability, mast cell activation), a control group would receive an equimolar dose of Mastoparan 17. The absence of effect in the control group would indicate that the effects of mastoparan are specific and not due to non-specific peptide toxicity or to the vehicle. However, such studies are not routine, and no specific data is available in the search results.

Non-cell-based assays for Mastoparan 17 are used to confirm its lack of interaction with G proteins. A common method is the GTPgammaS binding assay using purified G proteins (e.g., Gi1, Gi2, Go) or brain membrane preparations enriched in Gi/Go. Membranes (10-20 ug) are incubated with 0.1 nM 35S-GTPgammaS, 100 uM GDP, and increasing concentrations of mastoparan or Mastoparan 17 (0.1-100 uM) in assay buffer (20 mM HEPES pH 7.4, 100 mM NaCl, 5 mM MgCl2, 1 mM DTT, 0.1% BSA) for 60 minutes at 25degC. For purified G proteins (10-20 nM), the reaction is performed in a similar buffer with 0.5 uM GDP. The reaction is terminated by the addition of ice-cold stop buffer (20 mM Tris-HCl pH 8.0, 100 mM NaCl, 25 mM MgCl2) and rapid filtration through nitrocellulose membranes. The filters are washed and counted by liquid scintillation. Mastoparan (1-10 uM) typically stimulates 35S-GTPgammaS binding 2-5 fold over basal, whereas Mastoparan 17 shows no stimulation (or only basal levels). This assay directly measures the activation of G proteins by promoting the exchange of GDP for GTP. For a fluorescence-based assay, a fluorophore-labeled G protein (e.g., BODIPY-GTPgammaS or a Trp mutant of Galpha) can be used. For circular dichroism (CD) spectroscopy, the secondary structure of Mastoparan 17 can be analyzed to compare it with the active mastoparan. Peptides are dissolved in buffer (e.g., 10 mM phosphate buffer, pH 7.4, with or without 50% trifluoroethanol (TFE) to mimic a membrane environment). CD spectra are recorded from 190 to 260 nm. Mastoparan adopts an alpha-helical structure in the presence of TFE or membrane mimetics, while Mastoparan 17 may show a reduced propensity to form an alpha-helix or a different conformation, which could explain its lack of activity. This information is valuable for understanding the structure-activity relationship of G protein-activating peptides.

For cell-based studies, Mastoparan 17 is used as a negative control. Cells such as RBL-2H3 (rat basophilic leukemia) mast cells, HL-60 promyelocytic leukemia cells (differentiated into neutrophil-like cells), or CHO cells expressing Gi-coupled receptors are cultured in DMEM or RPMI with 10% FBS and 1% penicillin-streptomycin at 37degC in a 5% CO2 incubator. For mast cell degranulation assays, RBL-2H3 cells are seeded in 96-well plates (1×10^5 cells/well) and sensitized with IgE (anti-DNP IgE, 1 ug/mL) overnight. The next day, cells are washed and stimulated with the antigen (DNP-BSA, 10 ng/mL) as a positive control, or with various concentrations of mastoparan or Mastoparan 17 (0.1-50 uM) for 30 minutes at 37degC. Degranulation is measured by the release of beta-hexosaminidase: the supernatant is incubated with p-nitrophenyl-N-acetyl-beta-D-glucosaminide (1 mM) in citrate buffer (pH 4.5) for 60 minutes at 37degC, then the reaction is stopped with 0.1 M Na2CO3/NaHCO3 (pH 10), and the absorbance at 405 nm is measured. The percentage of degranulation is calculated relative to total cellular content (lysed cells with 0.1% Triton X-100). Mastoparan 17 should not induce significant degranulation above the basal level (typically <5-10%). For calcium mobilization assays, cells are loaded with Fluo-4 AM (2 uM) for 30 minutes at 37degC, washed, and resuspended in HBSS with Ca2+/Mg2+. Cells are plated in a 96-well black plate (1×10^5 cells/well), and the fluorescence (λex 485 nm, λem 525 nm) is measured in real-time using a fluorescence plate reader. Mastoparan (1-10 uM) induces a rapid increase in fluorescence (peak within 10-30 seconds), while Mastoparan 17 induces no significant change. For electrophysiology studies, the effect of the peptides on G protein-coupled inwardly rectifying potassium (GIRK) channels can be assessed in Xenopus oocytes co-expressing GIRK1/2 and Gi. Oocytes are injected with cRNA and incubated for 3-5 days. Two-electrode voltage-clamp recordings are performed. Mastoparan (1-10 uM) activates GIRK currents (inward current at -80 mV), while Mastoparan 17 does not. Mastoparan 17 serves as a critical control to demonstrate that the activation of GIRK channels by mastoparan is not due to non-specific membrane leakage or other artifacts.

In vivo protocols for Mastoparan 17 are not standard. For researchers wishing to use it as a negative control in a mouse model, an active mastoparan peptide (e.g., 1-10 mg/kg, i.p.) and Mastoparan 17 (same dose) are administered to separate groups of mice (e.g., n=6-8 per group). Parameters such as blood pressure, heart rate, body temperature, vascular permeability (Evans blue extravasation), and mast cell degranulation (histamine levels in plasma) are measured. Mastoparan 17 should have no significant effect compared to the vehicle control. Such experiments are not commonly performed, and the cost and limited availability of the peptide (as a research reagent) may be prohibitive. Mastoparan 17 is primarily a laboratory reagent for in vitro and ex vivo controls.

Pharmacokinetic data for Mastoparan 17 is not available, as it is not a drug. As a 14-amino acid peptide (MW 1494 Da), it is susceptible to rapid proteolytic degradation in biological fluids. The half-life in plasma would be on the order of minutes. The peptide is likely to be cleared by the kidneys and metabolized by peptidases. Oral bioavailability is negligible (<1%). For in vitro assays, the peptide is soluble in water (e.g., 50 mg/mL) and should be stored as a lyophilized powder at -20degC, protected from light and moisture. Stock solutions in water or PBS should be stored in aliquots at -80degC and used within 3-6 months to prevent degradation. The compound is stable as a powder for at least 2 years when stored at -20degC.

No toxicity data is available for Mastoparan 17. It is considered non-toxic because it is inactive. The active mastoparan peptide, at high doses, can cause hemolysis and mast cell degranulation, leading to hypotension, respiratory distress, and other adverse effects. Since Mastoparan 17 lacks this activity, it is not expected to be toxic in vivo at the doses used for control experiments. Standard safety precautions for handling peptides (gloves, lab coat, safety goggles) should be followed. The compound is for research use only and is not for human use.

[1]. Tucker EB, et, al. Mastoparan-Induced Intracellular Ca2+ Fluxes May Regulate Cell-to-Cell Communication in Plants. Plant Physiol. 1996 Jun;111(2):459-467.

Mastoparan 17 (Mas 17) is an inactive analog of the G protein-activating peptide mastoparan. It is commonly used as a negative control in experiments to validate the specificity of mastoparan's effects. The peptide has the sequence INLKAKAALAKKLL-NH2 (where the underlined residue is the critical substitution compared to the active mastoparan INLKALAALAKKLL-NH2). Mastoparan 17 is not a drug and is not FDA-approved. The product is a lyophilized white powder, soluble in water (e.g., 50 mg/mL) and DMSO. It should be stored at -20degC, protected from light and moisture, and is stable for at least 2 years. In solution, it should be stored at -80degC and used within 6 months. This peptide is a valuable tool for studying G protein-coupled receptor (GPCR) signaling, mast cell biology, and the mechanism of action of amphipathic peptides.

C70H132N20O15

1493.92

1493.02

145854-61-1

71312157

White to off-white solid powder

6.786

20

20

55

105

2800

15

CC[C@@H]([C@H](N)C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N)=O)CC(C)C)=O)CC(C)C)=O)CCCCN)=O)CCCCN)=O)C)=O)CC(C)C)=O)C)=O)C)=O)CCCCN)=O)C)=O)CCCCN)=O)CC(C)C)=O)CC(N)=O)=O)C

TUCDQOGRFHOSKG-ZWFWRLIFSA-N

InChI=1S/C70H132N20O15/c1-15-41(10)56(76)70(105)90-54(36-55(75)91)69(104)89-52(34-39(6)7)67(102)85-47(25-17-21-29-72)63(98)80-44(13)59(94)82-46(24-16-20-28-71)62(97)79-42(11)58(93)78-43(12)61(96)87-51(33-38(4)5)66(101)81-45(14)60(95)83-48(26-18-22-30-73)64(99)84-49(27-19-23-31-74)65(100)88-53(35-40(8)9)68(103)86-50(57(77)92)32-37(2)3/h37-54,56H,15-36,71-74,76H2,1-14H3,(H2,75,91)(H2,77,92)(H,78,93)(H,79,97)(H,80,98)(H,81,101)(H,82,94)(H,83,95)(H,84,99)(H,85,102)(H,86,103)(H,87,96)(H,88,100)(H,89,104)(H,90,105)/t41-,42-,43-,44-,45-,46-,47-,48-,49-,50-,51-,52-,53-,54-,56-/m0/s1

(2S)-N-[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-amino-4-methyl-1-oxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxopropan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxopropan-2-yl]amino]-1-oxopropan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxopropan-2-yl]amino]-1-oxohexan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]-2-[[(2S,3S)-2-amino-3-methylpentanoyl]amino]butanediamide

2934.99.9001

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 (e.g. under nitrogen), avoid exposure to moisture and light.

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.)