The rat recombined MsrA was prepared and purified from E. coli BL21, as described in our previous report (Wu et al., 2013b). In brief, MsrA coding region was ligated into the restricted pET‐32a (+) vector using phage T4 DNA ligase. BL21 cells were transformed with the recombinant plasmid and grown in LB medium. The cells were harvested, and cell lysis was applied to a 4 mL Ni‐Trap nickel‐chelating column. The N‐terminal His‐tag of recombinant peptide was removed using a Thrombin kit. The activity of recombinant MsrA was monitored by detecting both MetO‐reducing activity and methyl sulfoxide‐dependent oxidation of DTT.