Observed frequency of amino acid histogram similarity scores. The similarity score is scaled from 0 to 20 for convenience (i.e., 100% identical histograms would have a score of 20). Native refers to actual protein sequences and random to artificially generated sequences with the same overall amino acid composition and length distribution as native sequences. A) Data are shown for non-immune random, immune random, non-immune IDD, and immune IDD sets. B) Data are shown for random ordered and native ordered sequences.