Omit electron density maps of Lys-72 superposed on its double conformations. Hydrogen atoms are drawn in white. Numbers beside the blue dotted lines represent the distances between the two connected atoms in Angstroms. A, conformation A. The light blue mesh shows the Fo − Fc omit electron density map of conformation A of Lys-72 contoured at 3.5 σ. Conformations A and B of Lys-72 are drawn in green and transparent gray, respectively. B, both conformations A and B. The light blue mesh represents the Fo − Fc omit electron density map of Lys-72 contoured at 4.5 σ. Conformations A and B of Lys-72 are drawn in green and orange, respectively. C, conformation B. The light blue mesh represents the Fo − Fc omit electron density map of conformation B of Lys-72 contoured at 3.5 σ. Conformations A and B of Lys-72 are drawn in transparent gray and orange, respectively.