Figure 3.

Example of flexible motion for mode $m_7$ of the SARS-CoV-2 spike ecto domain (PDB: 6vxx) monomer at $E_{\text{cut}}=0.5\text{kcal/mol}$ with chain A denoted by yellow with its extreme structural positions superimposed and colored light orange/orange. The arrow indicates the range of movement for the dominant $\alpha$-helix structure in the spike ecto domain, from negative to positive movement. The smaller protein structures surrounding the large one 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.