Sequence Similarity : Non-homologous sequences (<30%) SEQUENCE SIMILARITY (%) 3r90A 4ox0A 4ox0D 3r90A 100 0 0 4ox0A 25 100 88 4ox0D 6 88 100 FOLD SIMILARITY (Z-SCORE) 3r90A 4ox0A 4ox0D 3r90A 36.1 0 0 4ox0A 0 10.3 8.3 4ox0D 0 8.3 10.2