Figure 2.

Differences between simulations of the Ca²⁺-bound and the apo structures of BtuB. (A) Root mean-square deviation (RMSD) of C_α atoms of BtuB's extracellular loops vs. time for the Ca²⁺-bound structure of BtuB (black) and the apo structure of BtuB (red), both in comparison to the CN-Cbl-bound structure of BtuB. (B) Root mean-square fluctuation (RMSF) vs. residue number for the two structures, colored as in A. (C) Comparison of the average structures, shown from the extracellular side, calculated from the last 20 ns out of the 30-ns simulations. The apo structure is shown in blue and the Ca²⁺-bound structure, with corresponding Ca²⁺ ions, in yellow.