Fig. 6
Ramachandman plot of the reference sequence. The CRM1 domain of the A/equine/Miami/1/1963(H3N8) reference strain is characterized by good quality in the disposition of the residues. Most of the amino acids are located inside the intrigues (0, − 90) for the alpha helices and (30, 90) beta sheets. The graph (or diagram) of Ramachandran can visualize all the possible combinations of dihedral angles Ψ (psi) against Φ (phi) in the amino acids of a polypeptide, and that contribute to the conformation of the structure of the proteins. This graph allows, therefore, to approximate a priori what will be the secondary structure of the peptide, since there are combinations of typical angles for each structure (α-helix and β-sheet). The conformation of the peptides is defined by assigning values for each pair of corners Φi, Ψi for each amino acid. In the second quadrant are the combinations of the leaf β, in the third quadrant are the right α helix and the loops; in the first quadrant the combinations of the left α helix