“…A -strand is a helical repeating pattern with two residues per turn (Creighton, 1993), implying that the residues that are next to each other in the amino acid sequence (K, K þ 1) fall on alternate (opposite) faces of the helix, and the residues that are adjacent to each other on the same face of the helix are separated by a residue in the sequence (K, K þ 2). For each alternate (K, K þ 1; 1-2, 2-3, 3-4, 4-5 and 5-6) and adjacent (K, K þ 2; 1-3, 2-4, 3-5 and 4-6) residue pairs in 139 amyloid (Amyl139) and 168 amorphous -aggregating hexapeptides (Amor168), we have computed frequencies of residue pair types (i,j, where i and j are the 20 amino acids found in proteins) by using the following equation (Gromiha, 2010;Ou et al, 2013):…”