Frequently Asked Questions (FAQ)

The amyloid peptide Aβ (1-42), or other amyloid mutants may form insoluble aggregates during storage. Aβ (1-42) is soluble in hexafluoroisopropanol (HFIP), DMSO, 0.1% aqueous ammonia, 50 mM TRIS ∙ HCl, or 1 mM NaOH. Reconstitution in HFIP or DMSO takes time whereas ammonia rapidly dissolves the peptide. The volatile solvent HFIP is usually evaporated leaving a residue of monomeric, soluble Aβ (1-42), which can be reconstituted with the chosen buffer at pH 7.4 to induce fibrillation. Aβ (1-42) solutions in DMSO or aqueous bases can be diluted directly with a working buffer.

Most peptides contain the basic functionalities: the guanidino group of Arg, the ε-amino group of Lys, the free N-terminus, and the imidazole moiety of His. These basic functionalities can form salts with acids. All our peptides are provided as trifluoroacetate salts unless specified otherwise. During cleavage from the carrier resin and purification, the peptide will react to the trifluoroacetic acid (a strong acid). Additional ion-exchange steps are needed to make the acetate salt or HCL salt form peptides. Some acidic peptides, containing Asp, Glu, phosphor group, or sulfotyrosine, can form salts with bases and may be provided as ammonium salts.