This is a fragment of beta-amyloid peptide amino acids 15 to 36. As a part of the full length b-amyloid peptide, fragment 15 to 36 adopts an alpha-helical conformation between these 15 and 36 residues with a kink or hinge at 25 to 27 according to some authors, and 15 to 20 and 24 to 34 by others.