Now to describe ..., which we call "5-tile encoding."
For example, the "5-tile code" of the alpha-helix considered before is computed as follows.
First of all, the two amino acids at both ends have no corresponding amino acid fragment. And "5-tile code" is computed for amino acids from AA[4] thorough AA[-4].
As shown on thr right, amino acid AA[4] corresponds to the fragment from AA[6] through AA[2] and its 5-tile code is DUDUD, which is denoted by "A". In the same way, amino acid AA[1] corresponds to the fragment from AA[3] through AA[-1] and its 5-tile code is also DUDUD, which is denoted by "A". And so on.
Finally, we obtain the sequence of straight "A" of length nine as 5-tile code of the alpha-helix, where hyphens stand for the two amino acids at both ends.