Figure 4.

Example of flexible motion for mode $m_7$ of the dimer of main protease (PDB: 6lu7) at $E_{\text{cut}}=2\text{kcal/mol}$. The crystal structure of the dimer is superimposed with its extreme structural positions according to mode $m_7$. Chain A is denoted yellow and its extremal structures colored as in Fig. 3 light orange/orange; chain B is indicated in blue with extremal positions in light and dark blue. The smaller protein structures show the initial (crystal) structure as well as the extremes ($+$, –) along the possible motion directions for $m_7$ in the same colors as in the superimposed structure.