![[Ala28]-β Amyloid(25-35) TFA](/upload/0319/V114718.png)
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| 1mg |
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| 5mg |
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| 10mg |
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| Other Sizes |
| Targets |
Unlike the full-length Abeta peptide, [Ala28]-beta Amyloid(25-35) does not have a defined pharmacological target for therapeutic intervention. Instead, it functions as a tool peptide for studying protein aggregation mechanisms. It is reported to accelerate the aggregation of firefly luciferase, an enzyme commonly used as a reporter. This is likely due to changes in surface charge and hydrophobicity resulting from the K28A mutation. The mechanism is non-specific and may involve electrostatic interactions, hydrophobic contacts, or surface-assisted aggregation. In wild-type Abeta(25-35), the positively charged lysine at position 28 influences peptide conformation and aggregation kinetics. Its replacement with uncharged alanine leads to faster aggregation kinetics.
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| ln Vitro |
In cell-free aggregation assays, [Ala28]-beta Amyloid(25-35) promotes the aggregation of firefly luciferase, leading to its inactivation. This effect is concentration-dependent and is observed at peptide concentrations of 10-100 microM. The peptide itself can form amyloid-like fibrils under appropriate conditions, as measured by Thioflavin T fluorescence. The aggregation kinetics of the mutant peptide are faster than those of the wild-type Abeta(25-35) fragment. No specific agonist or antagonist activity at receptors is associated with this peptide.
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| ln Vivo |
No therapeutic applications are intended for this peptide. It is used as a research tool in cell-free systems to study protein aggregation mechanisms. In vivo studies have not been reported for this particular mutant. However, wild-type Abeta(25-35) aggregates in vivo and induces neurotoxicity. The K28A mutation may alter these properties but has not been studied in animal models.
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| Enzyme Assay |
A Thioflavin T (ThT) aggregation assay is performed. The peptide is dissolved in hexafluoroisopropanol (HFIP), aliquoted, and dried under nitrogen to remove HFIP. Peptide films are stored at -80degC. For the assay, the peptide is dissolved in 10 mM NaOH to a concentration of 1 mM, then diluted to 50 microM in 10 mM sodium phosphate buffer (pH 7.4) containing 100 mM NaCl and 20 microM ThT. The reaction mixture is incubated at 37degC in a 96-well black plate with a clear bottom. ThT fluorescence (excitation=440 nm, emission=480 nm) is measured every 5 min with shaking between reads. The lag time, elongation rate, and final fluorescence are calculated. For electron microscopy, 10 microL of aggregated peptide (50 microM, aged for 24-48 hours) is placed on a carbon-coated grid, negatively stained with 2% uranyl acetate, and visualized. For luciferase aggregation assay, recombinant firefly luciferase (50 nM) is incubated with varying concentrations of [Ala28]-beta Amyloid(25-35) (0-100 microM) in 50 mM Tris-HCl pH 7.5, 10 mM MgCl2, and 1 mM DTT at 37degC for 2 hours. Aliquots are taken at 0, 30, 60, 90, and 120 min, and luciferase activity is measured by adding the substrate D-luciferin (0.5 mM) and ATP (1 mM) in a luminometer. Luminescence is recorded over 10 seconds. The percent of remaining activity is calculated relative to the untreated control.
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| Cell Assay |
For cell viability assays, the cell-based aggregation of luciferase is not directly relevant. For cell toxicity studies, the wild-type Abeta(25-35) fragment is tested in neuronal cell cultures. SH-SY5Y human neuroblastoma cells or primary rat cortical neurons are seeded in 96-well plates (2×10⁴ cells/well) and cultured for 48 hours. The cells are then treated with 1-50 microM peptide (pre-aggregated for 24-48 hours at 37degC) for 24-48 hours. Cell viability is measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Lactate dehydrogenase (LDH) release is measured to assess membrane damage. Intracellular reactive oxygen species (ROS) are measured using DCFH-DA dye. Apoptosis is assessed by Hoechst 33342 staining of condensed nuclei and by measuring caspase-3 activity. The K28A mutation may alter these toxic properties.
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| Animal Protocol |
In vivo toxicity models have not been reported for this mutant. For the wild-type Abeta(25-35), male Wistar rats (8-12 weeks, 250-300 g) are anesthetized, and 5-10 nmol of aggregated peptide (in 5 microL PBS) is injected intracerebroventricularly (ICV) bilaterally. Control animals receive scrambled peptide or vehicle. After 7-14 days, memory and learning are assessed using the Morris water maze (hidden platform) or passive avoidance test. After behavioral tests, hippocampal tissue is collected for measuring oxidative stress markers (MDA, GSH, SOD) and pro-inflammatory cytokines (IL-1beta, TNF-alpha). The K28A mutant has not been tested in vivo.
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| References | |
| Additional Infomation |
The peptide itself (free base) has a molecular weight of 1003.17. The amino acid sequence is: Gly-Ser-Asn-Ala-Gly-Ala-Ile-Ile-Gly-Leu-Met (GSNAGAIIGLM). In the wild-type Abeta(25-35) sequence (GSNKGAIIGLM), the lysine at position 28 is replaced by alanine in this mutant. The alanine substitution neutralizes the positive charge normally present at the 28th position, creating an electronegative mutant peptide according to some sources, while others describe it as electrically neutral. The TFA (trifluoroacetic acid) salt form is common for synthetic peptides. The CAS number of the free base is 173993-86-7. The peptide should be stored desiccated at -20degC and protected from light and moisture. It is soluble in DMSO and in water with sonication. For aggregation studies, the peptide should be pre-aggregated by incubation at 37degC for 48 hours in appropriate buffer.
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| Molecular Formula |
C42H74N12O14S.XC2HF3O2
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| Molecular Weight |
1003.17 (free base)
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| Related CAS # |
[Ala28]-β Amyloid(25-35)
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| Sequence |
Gly-Ser-Asn-Ala-Gly-Ala-Ile-Ile-Gly-Leu-MetGSNAGAIIGLM
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| Appearance |
White to off-white solid powder
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| Synonyms |
β(25-35)KA TFA
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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 (e.g. under nitrogen), avoid exposure to moisture and light. |
| 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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