Aβ 1-42, 42-residue fragment of amyloid precursor protein, has been found to be a major constituent of the senile plaques formed in the brains of patients with Alzheimer's disease and late Down's syndrome. Aβ 1-42 readily forms neurotoxic oligomers at physiological pH. On the other hand, the peptide shows antimicrobial activity. The sequence of H-1368 corresponds to the human, bovine, canine, feline, ovine, guinea pig, and rabbit Aβ42 peptide. The peptide has been used to detect amyloid β-protein multimers in the cerebrospinal fluid of Alzheimer's disease patients through fluorescence correlation spectroscopy. For detailed descriptions of the preparation of Aβ 1-42 monomers and protofibrils please see the papers of Jan, Hartley, and Lashuel, Stine et al. (2011), and of Broersen and colleagues. The findings of Ryan et al. indicate that 10% ammonia disaggregates Aβ42 more efficiently than HFIP.
