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Application Protocols
No manufacturer-validated protocols are provided for this item. The following are literature-style general procedures for common Aβ(3–40) applications. Adjust to your lab’s SOPs.
Preparation of monomeric stock (literature)
Dissolve lyophilized peptide in HFIP (0.5–1 mg/mL), incubate 30–60 min at RT. 2) Aliquot and evaporate to dryness under N2 or in a fume hood. 3) Dissolve the film in anhydrous DMSO to 1–5 mM. 4) Dilute into buffer immediately before use; final DMSO ≤1% v/v.
ThT aggregation assay (literature)
Mix peptide (10–20 µM final) with ThT (10 µM) in PBS, pH 7.4, in black 96-well plates. Incubate at 37°C with orbital shaking. Read Ex/Em 440/480 nm at intervals to capture lag, growth, and plateau phases. Include monomer-only, inhibitor, and seeded controls.
TEM sample preparation (literature)
At selected timepoints, apply 5–10 µL of sample to glow-discharged carbon grids, blot, negatively stain (e.g., 2% uranyl acetate), air-dry, and image.
LC–MS reference standard (literature)
Prepare accurately weighed aliquots, dissolve in 0.1% FA in water/ACN, and create calibration curves across the dynamic range of interest. Record exact peptide content and counterion information from the CoA for molarity calculations.
Item-specific validated dilutions or conditions: Not specified for this item; refer to CoA/Spec Sheet.
Biological Roles
Background provided for research context only (no medical or clinical claims).
Origin and composition (literature/general)
Aβ(3–40) is a truncated isoform of the human β-amyloid peptide, corresponding to residues 3–40 of the canonical Aβ sequence derived from proteolytic processing of the amyloid precursor protein (APP).
Biophysical behavior
Exhibits concentration-, pH-, ionic-strength-, and temperature-dependent self-assembly into soluble oligomers and β-sheet–rich fibrils. The central hydrophobic domain (KLVFFA) facilitates inter-peptide contacts.
N-terminal truncation can modulate aggregation kinetics and conformational preference relative to Aβ(1–40), influencing oligomer/fibril distributions in vitro (literature).
Interactions and assays
Binds fluorescent dyes (e.g., Thioflavin T) upon β-sheet formation; displays characteristic CD signatures (random coil to β-sheet transition) and FTIR amide I band shifts during aggregation.
Interacts with lipid membranes and metal ions (e.g., Zn2+, Cu2+) in a sequence- and condition-dependent manner (literature), which can modulate assembly pathways.
Analytical relevance
Serves as a reference analyte for immunoassays, LC–MS quantification, and seeding assays designed to study Aβ isoform specificity.
Note: Exact biological activity of this catalog item depends on sequence confirmation, termini, and post-synthetic modifications. Consult the CoA for item-specific attributes.
Buffer Applications
This product is a peptide reference material and is not itself a buffering reagent. Therefore, classic buffer system design (pKa selection, capacity) is not applicable.
Practical note (literature/general)
Aβ aggregation studies are typically conducted in physiologically relevant buffers such as PBS, HEPES, or Tris at pH 7.2–7.5. Ionic strength (e.g., 100–150 mM NaCl) significantly impacts kinetics.
When preparing peptide solutions, brief dissolution in DMSO or dilute NaOH followed by dilution into the chosen buffer can improve reproducibility.
For recipe-level buffer guidance, refer to standard PBS/HEPES/Tris formulations appropriate for your downstream assays.
Green Alternatives
Peptide handling sometimes employs fluorinated or high-toxicity solvents (e.g., HFIP, TFA). Where possible, opt for lower-impact alternatives without compromising experimental control over aggregation.
Greener choices (literature/general)
Use aqueous alkaline pretreatment (e.g., 1–10 mM NaOH) followed by rapid neutralization/dilution into buffered media to avoid HFIP.
Replace TFA-containing HPLC eluents with formic acid or acetic acid when MS compatibility and assay tolerance permit.
Minimize DMSO carryover in assays (<1% v/v) to reduce solvent footprint and interference.
Trade-offs
HFIP is highly effective at disaggregating Aβ but is a fluorinated VOC; aqueous or DMSO-based protocols may yield slightly higher residual oligomer content unless rigorously controlled.
Formic/acetic acid in RP-HPLC can alter retention and resolution relative to TFA; method re-optimization is typically required.
Comparison (literature)
HFIP pretreatment: maximal disaggregation; higher environmental burden; requires fume hood and solvent recovery if available.
Aqueous alkaline: minimal solvent burden; requires careful pH control to prevent peptide damage and to maintain reproducibility.
Implement solvent minimization (small-volume, high-concentration stocks), use closed systems for volatile solvents, and dispose of fluorinated wastes according to institutional environmental guidelines.
Pharmaceutical Uses
No therapeutic or clinical uses are claimed for this product. For research use only.
Employed as a reference standard in analytical method development (e.g., LC–MS peptide quantification, SEC) and in device/material compatibility studies evaluating peptide adsorption.
Used to benchmark excipient effects on peptide self-assembly in pre-formulation research (e.g., screening sugars, amino acids, and surfactants for their influence on aggregation kinetics).
Pharmacopeial status
No pharmacopeial monograph is associated with Aβ(3–40) to our knowledge (literature). Any use in regulated environments would require in-house specification, validated analytical methods, and stability data.
Practical considerations
If employing as a system suitability standard, document exact sequence, salt form, counterion content, and water content from the lot-specific CoA for accurate molarity and response-factor calculations.
All uses are restricted to laboratory research and method development; not for human or animal administration.
Physical Properties
Item-specific properties
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
Solubility: Not specified for this item; refer to CoA/Spec Sheet.
Other specifications (water, residual solvents, purity by HPLC, counterions): Not specified for this item; refer to CoA/Spec Sheet.
Literature/general properties for Aβ(3–40)
Sequence length: 38 residues (positions 3–40 of Aβ).
Approximate average molecular mass (literature estimate): on the order of ~4.1–4.2 kDa, depending on exact termini and counterions.
Aggregation behavior: prone to self-assembly into β-sheet oligomers and fibrils; apparent solubility is highly history-dependent (pretreatment and handling strongly influence monomer content).
Solvent behavior: dissolves in strong hydrogen-bonding/organic media (e.g., DMSO, HFIP) and in alkaline aqueous conditions (e.g., dilute NaOH) prior to dilution into buffers (literature practice). Direct dissolution in neutral buffers may lead to heterogeneous aggregates.
pI (qualitative): low-to-moderate, reflecting acidic residues offset by basic His/Lys; exact value depends on termini/protonation (literature).
Practical notes (literature)
Refractive index, logP, bp/mp are not typically defined for peptides; peptides are non-volatile solids that may be supplied lyophilized.
The presence of salts (TFA, acetate), water content, and counterions can shift the apparent mass; consult batch CoA for authoritative values.
Quality and Grades
Item-specific grade/purity
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
How peptide quality is typically defined (general guidance)
Purity by RP-HPLC: commonly reported as area % at 214/220 nm. Research-grade peptides are often supplied at >90–95% purity; crude grades may be lower depending on application.
Identity: confirmed by high-resolution MS (ESI/MALDI) and, where applicable, amino acid analysis or peptide sequencing.
Counterions/residuals: TFA or acetate salts may be present from purification; residual solvents and water content may be reported on CoA. These can influence solubility and bioassay outcomes.
Modifications: exact termini (free/blocked), potential N-terminal cyclization (e.g., E→pyroglutamate in some contexts), and oxidation state of Met are critical attributes often controlled or reported by vendors (literature). Consult the item’s CoA for your batch.
Implications for use
Aggregation studies are sensitive to minor impurities and history; ensure the purity and pretreatment protocol are appropriate for reproducible kinetics.
For quantitative standards (e.g., LC–MS peptide mapping), request mass balance, counterion content, and exact salt form for accurate molar calculations.
Documentation
Request lot-specific CoA/SDS for: purity (HPLC), identity (MS), sequence confirmation, residual solvents, water content, and recommended handling.
Reaction and Applications
As a research peptide, Aβ(3–40) is not a classical reagent for synthetic transformations. Its principal applications are in biophysical and biochemical studies of amyloid formation.
In vitro aggregation and fibrillization (literature/general)
Kinetic assays: monitor Thioflavin T (ThT) fluorescence to quantify β-sheet formation; lag phase and growth rates are sensitive to peptide history, ionic strength, and temperature.
Seeding experiments: use pre-formed fibril seeds to study secondary nucleation and elongation mechanisms.
Morphology characterization: AFM, TEM, and cryo-EM to visualize oligomers/fibrils produced under defined conditions.
Binding and inhibition studies
Screen small molecules, peptides, or antibodies for modulation of aggregation pathways (nucleation, elongation, secondary nucleation) by measuring ThT, CD, DLS, or NMR changes.
Analytical standards and method development
Use as a positive control or calibration standard in LC–MS peptide mapping, SEC, and capillary electrophoresis methods targeting Aβ isoforms.
Practical tips (literature)
Use freshly prepared, filtered monomer stocks to reduce batch-to-batch variability.
Normalize ionic strength (e.g., 100–150 mM NaCl) and pH (7.2–7.4) across experiments.
Avoid surfactants unless validated; some detergents alter nucleation kinetics.
Note: No manufacturer-specific applications were provided for this item; the above reflects common research uses reported in the literature.
Reaction Conditions
Not a classical reagent for organic synthesis; however, standardized in vitro assembly conditions are widely reported for Aβ peptides (literature/general):
Monomer preparation
Pretreat with HFIP (disaggregate), evaporate to film, then dissolve in anhydrous DMSO to prepare a concentrated stock (e.g., 1–5 mM). Alternatively, dissolve directly in dilute NaOH (1–10 mM) before neutralization.
Aggregation assays (typical literature conditions)
Concentration: 5–100 µM peptide.
Buffer: PBS, HEPES, or Tris, pH 7.2–7.5; ionic strength 100–150 mM NaCl as required.
Temperature: 25–37°C; agitation (orbital shaking or quiescent) modulates kinetics and morphology.
Detection: ThT fluorescence (5–20 µM ThT), CD spectroscopy, DLS; endpoint confirmation with TEM/AFM.
Time course: lag phases from minutes to hours; plateau typically within hours to days depending on conditions and seeding.
Metal/ligand effects
Zn2+ or Cu2+ can alter kinetics and aggregate morphology; include matched metal-free controls (chelex-treated buffers) when metal effects are not under study.
These conditions are provided as general literature guidance. Optimize empirically for your system and consult primary literature for isoform-specific parameters. This item’s CoA does not specify recommended assay conditions.
Safety and Handling
Item-specific hazard information
Signal word: Not specified for this item; refer to SDS.
H-statements: Not specified for this item; refer to SDS.
GHS classification: Not specified for this item; refer to SDS.
Pictograms: Not specified for this item; refer to SDS.
General laboratory precautions (peptide, research use)
For research use only. Avoid inhalation of powders and contact with skin/eyes. Handle in a clean, dry environment to minimize contamination and moisture uptake.
PPE: lab coat, nitrile gloves, safety glasses. Use a dust mask or work in a ventilated enclosure when handling dry powder to prevent aerosol exposure.
Hygiene: wash hands thoroughly after handling. Do not eat, drink, or smoke in work area.
Handling considerations (literature/general for Aβ peptides)
Aggregation risk: Peptide can aggregate; prepare fresh solutions and avoid repeated freeze–thaw cycles. Filter through low-protein-binding membranes (0.22 µm) when monomeric solutions are required.
Avoid strong acids/bases and oxidants during storage; methionine-containing sequences can be oxidation-sensitive—use low-oxygen handling if oxidation state is critical (literature).
First-aid overview (general)
Eye/skin contact: rinse with water for several minutes; remove contaminated clothing. Seek medical advice if irritation persists.
Inhalation: move to fresh air. Obtain medical attention if symptoms occur.
Ingestion: rinse mouth with water; seek medical advice.
Always consult the SDS accompanying your lot for authoritative hazard, spill, and disposal guidance.
Solvent Selection
This product is a self-assembling peptide; solvent choice primarily aims to control aggregation and obtain monomeric stock solutions.
Item-specific solubility: Not specified for this item; refer to CoA/Spec Sheet.
Literature/general guidance for Aβ(3–40)
Primary dissolution
HFIP (hexafluoro-2-propanol): disrupts secondary structure and disaggregates pre-formed assemblies. Often used to prepare monomer films; evaporate HFIP and re-dissolve the film.
DMSO (anhydrous): produces concentrated monomeric stocks (e.g., 1–5 mM) that can be diluted into aqueous buffers. Minimize water to prevent premature aggregation.
Dilute NaOH (e.g., 1–10 mM): can aid initial dissolution before rapid neutralization/dilution into buffer.
Aqueous buffers
PBS, HEPES, Tris at pH 7.2–7.5 are common assay media. Gentle sonication and filtration (0.22 µm, low-binding) may improve clarity.
Incompatibilities
Strong acids and multivalent cations can promote aggregation. Avoid residual TFA when assaying cation-sensitive systems.
Selection tips
Choose HFIP/DMSO pretreatment when strictly monomeric starting material is required (e.g., kinetic nucleation assays).
For routine fibrillation assays, controlled dilution from DMSO into buffer at target ionic strength yields reproducible aggregation kinetics.
DMSO: convenient, miscible; can interfere with some assays above ~1–2% v/v.
Aqueous alkaline: minimal organics; may cause local hydrolysis if not promptly neutralized.
Storage and Reconstitution
Item-specific storage/shipping
Storage Conditions: Store at -20°C.
Shipped In: Ice chest + Ice pads.
General reconstitution guidance (literature/general for Aβ peptides)
Upon receipt, allow container to equilibrate to room temperature before opening to prevent condensation. If lyophilized, briefly centrifuge to collect material.
For monomeric stocks: pretreat with HFIP to disaggregate if needed; evaporate and re-dissolve the film in anhydrous DMSO (1–5 mM). Alternatively, dissolve in dilute NaOH, then dilute/neutralize into buffer.
Prepare single-use aliquots in low-binding tubes to avoid adsorption and repeated freeze–thaw.
Storage of solutions (literature)
Short term: keep on ice during use; minimize time at room temperature to limit aggregation.
Long term: aliquots can be stored at -80°C to best preserve monomeric state; avoid repeated freeze–thaw cycles. For this item, the stated storage temperature is -20°C; follow the label/CoA for stability claims and adjust only if your protocol requires different conditions validated in your lab.
Stability notes
Protect from light and air when feasible; methionine oxidation and N-terminal modifications can occur over time (sequence-dependent; literature). Use inert gas overlay for dry films.
Always consult the lot-specific CoA for exact solvent recommendations, concentration limits, and stability data.
Structure and Identity
Research-grade peptide corresponding to the β-amyloid sequence residues 3–40 (Aβ(3–40)).
Item-specific identifiers
SKU: A1444630
CAS: 157884-70-3
Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
SMILES: Not specified for this item; refer to CoA/Spec Sheet.
Structural features (literature/general)
Type: 38-residue peptide (positions 3–40 of the human β-amyloid precursor sequence).
Typical sequence for human Aβ(3–40): EFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVV (literature).
Functional groups: multiple amide bonds (peptide backbone), side chains including acidic (Glu, Asp), basic (His, Lys), aromatic (Phe, Tyr if present; here Phe), and hydrophobic (Val, Ile, Leu, Ala, Gly, Met) residues.
Net charge at neutral pH (literature): modestly negative to near-neutral depending on ionic strength and protonation of His/Glu/Asp.
2D description (literature/general)
Linear polypeptide chain with N-terminal Glu (E) at position 3 of the full Aβ, C-terminal Val (V) at position 40. The backbone consists of repeating –NH–CH(R)–CO– units; side chains define amphiphilic character with a central hydrophobic core (KLVFFA) known to promote self-assembly and β-sheet formation in vitro.
Note: Peptides typically do not have single canonical SMILES/InChI for the entire sequence in catalog listings; consult the CoA for exact sequence, termini, and any modifications specific to this item.
Synthetic Utility
As a defined peptide, Aβ(3–40) is primarily a target/analyte rather than a synthetic reagent. Nevertheless, it has utility in synthetic and analytical method development.
Utility in peptide chemistry (literature/general)
Benchmark for SPPS process validation: replicate synthesis using Fmoc/tBu SPPS to validate coupling/deprotection protocols for hydrophobic, aggregation-prone sequences.
RP-HPLC method development: challenging hydrophobic core (KLVFFA…) provides a stringent test for gradient design, ion-pair selection (TFA vs FA/AA), and column selection (C18/C8/phenyl).
MS calibration/optimization: multi-basic and acidic residues enable evaluation of charge-state distributions and in-source aggregation/fragmentation behavior.
Conjugation and labeling studies
Serves as a scaffold for N- or C-terminal labeling (e.g., fluorescent tags, biotin) to study assembly pathways, binding interactions, or surface immobilization.
Retrosynthetic insights
Segment condensation strategies (e.g., native chemical ligation with auxiliary sequences) can be explored using truncated fragments of Aβ to improve yields for highly hydrophobic stretches (literature).
Note: No item-specific reactivity or stabilizers are provided. If performing derivatizations, confirm termini (free vs protected) and counterions on the lot-specific CoA.
Target Specificity
This listing is a peptide material, not an antibody or affinity reagent. No target-binding specificity data are provided for this item.
Item-specific data: Not specified for this item; refer to CoA/Spec Sheet.
General note (literature)
When used as an analyte in immunoassays, Aβ(3–40) may exhibit distinct recognition compared to Aβ(1–40) depending on antibody epitope mapping; verify antibody compatibility with the truncated N-terminus.
For application-specific binding data (e.g., epitope recognition by particular clones), consult the antibody supplier’s documentation.
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