Ramachandran plot of intermediate structures for pyrophosphokinase morph. The Ramachandran plot  of the intermediate structure which occurs halfway in the morph from 1DY3 to 1RAO. Angles that occur in the core regions are represented as plus signs while outliers are represented as asterisks. Glycines are represented as squares. The absent atoms in the backbone and side chains of each intermediate structure were reconstructed using Maxsprout , and energy minimization was performed using Swiss-PDB viewer .