Figure 3. The binding mode observed most frequently in the MD simulations corresponds to the one in the X-ray structure.

Two binding poses of BUT from the red subbasin (carbon atoms in green) are shown together with the pose of BUT in the crystal structure (carbon atoms in blue) upon optimal overlap of the C atoms of FKBP. The surface of FKBP is colored according to atom type with carbon, oxygen, and nitrogen atoms in yellow, red, and blue, respectively. The hydrogen bond between the NH of Ile56 and the carbonyl oxygen of BUT is shown by green dashed lines.