Comparative studies on peptides representing the so-called tachykinin-like region of the Alzheimer Aβ peptide [Aβ(25-35)]

Abstract

In an attempt to answer the question of whether or not the so-called tachykinin-like region of the Alzheimer β-amyloid protein [Aβ(25-35)] can act as a tachykinin, the sequences Aβ(25-35), Aβ(25-35)amide and their norleucine-35 and phenylalanine-31 analogues were synthesized. These peptides were examined with ligand binding studies, electron microscopy, CD and NMR. In all cases some differences were found between the Aβ(25-35) analogue and the corresponding Phe31 peptide. In addition, in ligand displacement studies on tachykinin NK1 receptors, only the Phe31 analogue showed activity comparable to that of genuine tachykinins. We conclude that peptides based on Aβ(25-35) but with a Phe residue at position 31 do display properties typical of a tachykinin, but that peptides with Ile at this position do not.