The DMS conformation from docking experiment indicated that DMS could easily bind to the catalytic pocket of MsrA (Fig. 1A), which was composed of side chains of Cys72, Phe73, Trp74, Tyr103, and Glu115. To confirm this point, firstly, we asked whether DMS could directly bind to the pocket of MsrA. The active rat recombined MsrA protein (3 μm) was incubated with different concentrations of DMS, and its binding was measured by fluorescence anisotropy. As shown in Fig. 1B, the anisotropy value of MsrA reduced with the increasing amount of DMS at near‐physiological concentrations (1–5 μm), indicating a direct binding of DMS to MsrA.