β-Amyloid (13-27) , CAS No.148270-13-7

CAS: 148270-13-7 Cat. No.: A1444441 Fórmula: C₈₄H₁₂₆N₂₄O₂₄ Peso molecular: 1856.05

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Visão geral

β-Amyloid (13-27) is a peptide consisting of amino acid of 13 to 27 of beta amyloid protein.

Specifications

Condições de armazenamento de armazenamento

Store at -20°C

Enviado em

Ice chest + Ice pads

Este produto requer transporte de cadeia fria. Serviços terrestres e outros serviços econômicos não estão disponíveis.

Nomes e identificadores

Peso molecular

1856.05

Application Protocols

• Tested applications (e.g., WB, IHC, IF, ELISA, aggregation assays), recommended dilutions, and positive controls: Not specified for this item; refer to CoA/Spec Sheet and primary literature.
• General note: Because Aβ13–27 is commonly applied in aggregation and biophysical assays, users should tailor protocols (stock preparation, buffer selection, concentration, temperature, agitation) to their specific instrumentation and endpoints. No item-specific, validated protocols are provided.

Biological Roles

• Biological context (literature): The Aβ13–27 segment captures the central hydrophobic core (LVFFA) of human amyloid-β, a peptide derived from proteolytic processing of amyloid precursor protein (APP). This region is strongly implicated in β-sheet formation and self-assembly phenomena studied in vitro.
• Functional features of the 13–27 region (literature/general):
  • Aggregation driver: LVFFA motif stabilizes inter-strand contacts and nucleation. Variations in ionic strength, pH, and cosolvents modulate kinetics.
  • Metal interaction: N-terminal histidines (positions 13–14 within this fragment) can coordinate transition metals (e.g., Cu2+, Zn2+), influencing redox chemistry and assembly behavior in model systems.
  • Membrane association: Hydrophobic residues facilitate interactions with lipid bilayers and micelles; used to investigate peptide–membrane perturbations and secondary structure in membrane-mimetic environments.
• Use in biology research: Serves as a defined-length probe to dissect sequence determinants of Aβ self-assembly, to perform epitope mapping for antibodies recognizing the central Aβ region, and to calibrate biophysical assays (ThT, CD, FTIR) without full-length Aβ complexity.
• Important note: All roles and uses above refer to basic research and biophysical/biochemical studies; no clinical or diagnostic use is implied.

Buffer Applications

• This product is not a buffering reagent. However, buffer choice critically affects peptide solubility, charge state, and aggregation (general guidance):
• Common buffers for Aβ fragment studies (literature):
  • PBS (pH 7.2–7.4): Physiological ionic strength; may promote aggregation of hydrophobic segments.
  • HEPES (pH 7.0–8.0): Minimal metal chelation; good for fluorescence and CD.
  • Tris (pH 7.0–8.5): Widely used but can weakly coordinate metals and may interfere in metal-binding studies.
  • Acetate or citrate (pH 4–6): Useful for protonating His side chains; can reduce aggregation.
• Practical tips:
  • Filter and degas buffers; prepare fresh to limit microbial contamination and trace metal introduction.
  • For metal-binding assays, use metal-free reagents and chelex-treated water; avoid phosphate if precipitating metals.
  • Control ionic strength and pH precisely; small changes can strongly shift aggregation kinetics.
• Item-specific buffer recommendations, pH limits, and formulations: Not specified for this item; refer to literature and optimize empirically.

Green Alternatives

• Context: This product is a peptide, not a process solvent. However, dissolution/disaggregation steps often use organic solvents (e.g., HFIP, TFE, DMSO) that have environmental, safety, or waste-disposal considerations.
• Greener handling strategies (literature/guidance):
  • Prefer aqueous dissolution at adjusted pH (e.g., dilute NH4OH or buffer above pH ~8) to obviate halogenated/alcoholic solvents.
  • Minimize HFIP/TFE usage by using brief contact times and complete removal (N2 stream + vacuum) before assays.
  • Use ethanol or isopropanol pre-wetting in limited cases where effective, recognizing they are less potent disaggregants than HFIP/TFE.
  • Employ micro-scale preparation and aliquoting to reduce chemical waste.
• Comparison (general):
  • HFIP: Excellent disaggregant; high toxicity, specialized disposal.
  • TFE: Effective helix inducer; flammable; better but still non-green.
  • DMSO: Widely used, relatively benign but persistent; small volumes recommended.
  • Aqueous basic media: Greenest option; may alter peptide charge/structure—optimize pH and rapidly neutralize after dilution.
• Note: Item-specific solvent restrictions are not specified. Select the least hazardous solvent system consistent with your biophysical objectives and validate impacts on aggregation.

Pharmaceutical Uses

• This product is supplied for research use only; no clinical, diagnostic, or therapeutic applications are claimed or supported.
• Potential formulation roles (general research context):
  • Reference peptide for analytical method development (e.g., LC–MS peptide mapping, assay calibration) focused on Aβ central-region epitopes.
  • Model analyte for excipient–peptide interaction studies or peptide delivery research in preclinical settings.
• Pharmacopeial status, excipient monographs, and GMP applicability: Not specified for this item. If regulated applications are contemplated, obtain detailed specifications, impurity profiles, and perform appropriate qualification under relevant quality systems.

Physical Properties

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• State: Typically supplied as a lyophilized solid or film for peptides (general/literature). Item-specific form not specified.
• Solubility (literature/guidance):
  • Water/buffers: Variable. Aβ central fragments can be poorly soluble near neutral pH due to the LVFFA core; improved solubility is often achieved with slight basification (e.g., dilute NH4OH or NaOH), or initial dissolution in organic cosolvents (DMSO, HFIP) followed by dilution into buffer.
  • Organic solvents: DMSO generally dissolves to high concentration; HFIP or TFE can disaggregate pre-formed aggregates (literature). Use minimal volumes and promptly dilute into aqueous media as required by the assay.
• pKa values (literature, residue-level): His side chains pKa ~6.0; Lys ε-NH3+ pKa ~10.5; Asp/Glu side-chain pKa ~3.9/4.3. Net charge is highly pH-dependent.
• Aggregation/assembly (literature): The LVFFA motif favors β-structure and aggregation; pre-treatments (HFIP, basic stock) often used to generate monomeric starting material.
• Molecular weight: Not specified for this item; refer to CoA/Spec Sheet. As a reference, the calculated average molecular weight for the unmodified free-base peptide HHQKLVFFAEDVGSN is ~1,728 Da (literature calculation); actual value depends on salt form and terminal states.
• Other physicochemical data (BP/MP, density, logP, refractive index): Not typically defined/reported for peptides of this size; not specified for this item.

Quality and Grades

• Grade/purity: Not specified for this item; refer to CoA/Spec Sheet.
• Typical quality attributes for synthetic research peptides (general):
  • HPLC purity (often >95% for analytical/research grade) measured by reversed-phase chromatography; area% purity does not correct for counterions or water.
  • Identity confirmed by ESI/TOF-MS or MALDI-TOF. High-resolution MS may be provided for exact mass confirmation.
  • Counterion/salt form (e.g., TFA, acetate) significantly affects net mass and solubility; exact salt form for this item is not specified.
  • Residual solvents/reagents (e.g., TFA, piperidine) and water content may be reported on the CoA; not specified here.
• Stabilizers/additives: Not specified for this item. Many Aβ fragments are supplied additive-free to avoid perturbing aggregation studies.
• What the grade implies (general): Higher peptide grades support biophysical and aggregation studies with minimized impurity-driven nucleation. Where applicable, low-UV background and metal content can be important for spectroscopic or metal-binding assays; consult CoA for this item.

Reaction and Applications

• Primary research applications (literature, no clinical claims):
  • Model system for β-amyloid self-assembly: Residues 13–27 encompass the LVFFA core implicated in β-structure and fibrillization. Used in seeding, nucleation, and elongation studies monitored by ThT fluorescence, CD, EM/AFM.
  • Biophysical characterization: NMR, FTIR, SAXS/WAXS, and DSC to probe secondary structure transitions and solvent/pH effects.
  • Surface and interface studies: SPR, QCM-D, and ITC to quantify interactions with membranes, gangliosides, or inorganic surfaces.
  • Metal-binding/oxidation chemistry: Histidine-rich N-terminus can coordinate Cu(II)/Zn(II); used to study redox and coordination effects on aggregation (literature).
• Conjugation/derivatization (general peptide chemistry):
  • N-terminus or Lys side chain enables amide coupling (NHS-ester, carbodiimide) to dyes, PEGs, or surfaces. Sequence-specific modifications alter aggregation—validate post-modification behavior.
• Practical tips:
  • Use freshly prepared, monomeric stocks. Filter (0.22 µm) when compatible.
  • Avoid metal contamination (use metal-free waterware) in metal-binding studies.
  • Control ionic strength and agitation; both strongly influence aggregation kinetics.
• Manufacturer Applications: Not specified for this item.

Reaction Conditions

• As a peptide reagent, this product is not used in classical small-molecule synthetic reactions. However, typical experimental conditions for biophysical assays with Aβ13–27 are as follows (literature/general guidance; optimize empirically):
• Stock preparation:
  • Disaggregate with HFIP, dry to a film, desiccate, then dissolve to 1–5 mM in DMSO or dilute base (e.g., 10–50 mM NH4OH/NaOH). Filter if compatible.
• Aggregation kinetics assays (e.g., ThT):
  • Concentration: 5–100 µM peptide in PBS or HEPES; ThT ~10–20 µM.
  • Temperature: 25–37°C; agitation/orbiting/shaking accelerates nucleation.
  • Time: Minutes to days depending on conditions; monitor fluorescence (Ex ~440–450 nm, Em ~480–490 nm) and confirm with orthogonal methods (CD, EM).
• Secondary structure analysis:
  • CD: 190–260 nm in low-UV-absorbing buffers (HEPES recommended); keep absorbance <1 AU.
  • FTIR: Amide I′ band (1600–1700 cm−1) for β-structure content.
• Metal-binding investigations:
  • Use metal-free buffers; titrate Cu2+/Zn2+ and monitor by UV–Vis, ITC, or EPR (for Cu2+).
• Exact, item-specific recommended conditions are not provided; consult primary literature and adjust for your instrumentation.

Safety and Handling

• GHS classification, signal word, H-statements, pictograms: Not specified for this item; refer to the SDS for authoritative safety information.
• General laboratory precautions (peptide, research use):
  • Avoid inhalation of powders/aerosols; handle in a fume hood or biosafety cabinet if dusting may occur.
  • Wear appropriate PPE: lab coat, nitrile gloves, and safety glasses.
  • Prevent contamination with moisture; peptides may be hygroscopic. Work quickly with desiccated materials.
• Incompatibilities/conditions to avoid (general):
  • Strong oxidizers and extreme pH can degrade peptide backbones or side chains.
  • Repeated freeze–thaw of solutions promotes aggregation/degradation; aliquot stocks.
  • Light is generally less critical than for chromophoric drugs, but prolonged UV exposure can promote oxidation (e.g., of His) (literature).
• First-aid overview (general): If inhaled, move to fresh air. If on skin/eyes, rinse with water for several minutes. If ingested, rinse mouth; seek medical attention. Always follow institutional SOPs.
• Decomposition/thermal stability: Peptides can degrade via hydrolysis, oxidation, or deamidation; store as directed to maintain integrity.
• Research use note: For research use only. Not for human or veterinary use.

Solvent Selection

• Compound class: Amphiphilic peptide fragment with a hydrophobic LVFFA core; solubility is pH- and solvent-dependent (literature).
• Practical dissolution strategy (literature guidance):
  • Monomerization: Pre-treat with HFIP or TFE to disrupt aggregates; evaporate to a thin film under N2 and vacuum-desiccate before reconstitution.
  • Stock solutions: Use DMSO (high solubility) or minimal 0.1–1% NH4OH/NaOH in water to achieve clear solution; promptly dilute into buffer while vortexing.
  • Working buffers: PBS, HEPES, or Tris are common; adjust ionic strength and pH to experimental needs.
• Miscibility/compatibility (general): DMSO is fully miscible with water; HFIP/TFE are miscible with water/alcohols but can affect protein structures—remove or dilute to negligible levels before assays.
• When to choose alternatives:
  • For aggregation kinetics: Prefer aqueous buffers with minimal organic content to avoid altering nucleation/elongation.
  • For membrane or liposome studies: Use buffers compatible with lipids; minimize HFIP/TFE carryover.
• Notes: Item-specific solvent recommendations and concentration limits are not specified; verify solubility empirically at intended assay pH and ionic strength.

Storage and Reconstitution

• Storage (item-specific): Store at -20°C. Shipped in ice chest with ice pads.
• Long-term handling (general peptide guidance):
  • Keep tightly sealed under dry, inert conditions; include desiccant. Protect from moisture uptake.
  • For extended storage, -20°C or below is typical for lyophilized peptides. Avoid frost-free freezers that cycle temperatures.
• Reconstitution (general/literature):
  • To obtain monomeric peptide, optionally pre-treat solid with HFIP, dry to a film, and desiccate. Dissolve first in DMSO or minimal dilute base (e.g., 0.1–1% NH4OH/NaOH), then dilute into buffered aqueous media with gentle mixing.
  • Target concentration and solvent system depend on assay; verify clarity and absence of visible particulates. Filter through low-protein-binding membranes if compatible.
• Aliquoting and stability:
  • Prepare single-use aliquots to avoid repeated freeze–thaw. Store frozen aliquots at -20°C or lower.
  • Working solutions are best used same day; stability depends on pH, temperature, and ionic strength. Empirically determine shelf-life for your conditions.
• Research use only: Not for human or veterinary use.
• Any item-specific stabilizers or excipients: Not specified for this item; refer to CoA/Spec Sheet.

Structure and Identity

• Item-specific identifiers:
  • CAS: 148270-13-7
  • SKU: A1444441
  • Molecular Formula: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.
  • SMILES: Not specified for this item; refer to CoA/Spec Sheet.
  • InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
• Compound type: Synthetic peptide fragment corresponding to the central region of human β-amyloid (Aβ) spanning residues 13–27.
• Sequence (literature): HHQKLVFFAEDVGSN (Aβ13–27, literature sequence derived from the human Aβ1–42 primary structure). Any post-synthetic modifications, terminal protections, salt forms, or isotopic labels for this item are not specified.
• Structural features (general peptide chemistry):
  • Contains two N-terminal histidines (potential metal-binding and pH-sensitive side chains), Lys/Glx residues (ionizable), and a hydrophobic core LVFFA known to drive self-assembly (literature).
  • Functional groups: multiple amide bonds (peptide backbone), ionizable side chains (His, Lys, Glu, Asp), and terminal amine/carboxylate if unprotected (item-specific termini not specified).
• 2D structure description (general): A linear polypeptidic chain of 15 L-amino acid residues connected by trans amide bonds; side chains alternate along the backbone, with an N-terminal imidazole-containing histidine pair and a central phenylalanine-rich hydrophobic segment.

Synthetic Utility

• Role in synthesis (general peptide chemistry):
  • Serves as a defined sequence module for structure–activity relationship (SAR) studies via single-point mutations, truncations, or residue substitutions to probe assembly determinants.
  • Useful as a scaffold for conjugation (e.g., N-terminal/Lys-side-chain coupling) to fluorophores, affinity tags, PEGs, nanoparticles, or surfaces to create biophysical probes.
  • Can act as a seed/template in co-assembly experiments with analogs to study cross-interactions.
• Methods of preparation (literature): Commonly prepared by Fmoc solid-phase peptide synthesis (SPPS) with careful handling of hydrophobic LVFFA stretch (double couplings, pseudoproline/fragment condensation strategies). Purified by RP-HPLC and characterized by MS.
• Transformations and derivatizations:
  • Terminal capping (Ac-, -NH2) to modulate net charge and aggregation.
  • Site-specific labels (e.g., fluorescein on Lys) for imaging and kinetics.
  • Stable isotope labeling for NMR/MS quantitation.
• Retrosynthetic value: Provides a mid-length Aβ segment enabling modular assembly of longer Aβ constructs via native chemical ligation or segment condensation strategies in methodological research.
• Item-specific protecting groups, counterions, or labels: Not specified for this item.

Target Specificity

• Antigen/epitope details, clone information, species reactivity, isotype: Not specified for this item.
• Note: This product is a peptide fragment and not an antibody. If used as an antigen for antibody production or as a blocking peptide, epitope mapping should be validated experimentally. Item-specific validation data are not provided.