β-Amyloid (1-42), human, is a 42-amino acid peptide integral to the pathogenesis of Alzheimer disease.

Amyloid β-Peptide (1-42) human is a 42-amino acid peptide which plays a key role in the pathogenesis of Alzheimer disease. Application of Amyloid β-Peptide (1-42) human (1 to 10 μM) in the bathing solution does not change delayed rectifier K+-current and leakage current, but enhances inactivation of Са2+-current and blocks Са2+-dependent К+-current[1]. At 2.5 μM concentration, Amyloid β-Peptide (1-42) human reduces viability of SH-SY5Y cells to 65%. Results show that Amyloid β-Peptide (1-42) human localizes in both the cytoplasm and nucleus of SH-SY5Y cells after 30 min of incubation and after 8 h. In the latter, large accumulations of Amyloid β-Peptide (1-42) human are seen in the cytoplasm and in the nucleus. Increased APP mRNA levels are also detected upon Amyloid β-Peptide (1-42) human treatment[2].

Preparation of Monomeric Aβ42 from Lyophilized Peptide [2]

The following procedure is a recommended guideline and may require optimization based on the requirements of specific downstream applications.

1. Equilibrate lyophilized Aβ42 peptide to room temperature. Briefly centrifuge at 1,500 × g for 30 seconds to collect material at the bottom of the tube.

2. Add ice-cold hexafluoroisopropanol (HFIP) at a ratio of 100 µL per 0.5 mg Aβ42. Incubate the mixture on ice for 30 minutes to fully solubilize the peptide.
Caution: HFIP is volatile and toxic. Perform all handling in a certified chemical fume hood with appropriate personal protective equipment.

3. Dispense the peptide/HFIP solution into 20 µL aliquots, allowing solvent to evaporate in a fume hood for 2-3 hours until a uniform peptide film is formed. Films may be stored at −20 °C or −80 °C.
Note: If available, vacuum desiccation or nitrogen gas blowing is recommended.

Preparation of Aβ42 Oligomers

1. Dissolve the peptide film in 10 µL of freshly prepared DMSO (Cat. No. T0341). Sonicate in a water-bath sonicator for 10 minutes at room temperature to facilitate monomerization.

2. Dilute the DMSO stock with 190 µL of 50 mM Tris-HCl buffer (pH 7.4) and mix gently by pipetting to avoid introducing air bubbles.

3. Centrifuge the solution at 20,000 × g for 20 minutes at 4 °C to remove insoluble aggregates. Carefully transfer the supernatant (monomer-enriched fraction) to a clean tube.

4. Incubate the collected supernatant at 4-8 °C for 24-48 hours to promote controlled oligomerization. Centrifuge again at 20,000 × g for 20 minutes at 4 °C to remove newly formed large aggregates. Use the final supernatant for experiments following dilution (typically 10-200 fold depending on assay requirements).

Warning:
Aβ42 oligomeric assemblies are unstable and prone to further aggregation. Fresh preparation is strongly recommended. For extended storage, peptides should remain in film form at −20 °C or −80 °C rather than in solution.

5. Quantify peptide concentration using a bicinchoninic acid (BCA) protein assay (Cat. No. C0050), following the manufacturer’s instructions.

Note: The protocol is derived from published literature and is provided for reference only. TargetMol has not independently validated the method.