Has an important function as a repair enzyme for proteins that have been inactivated by oxidation. Catalyzes the reversible oxidation-reduction of methionine sulfoxide in proteins to methionine (By similarity). Peptide methionine sulfoxide reductase MsrA 176 Peptide-methionine (S)-S-oxide reductase msrA MPEEIATLAGGCFWCTEAAFKLLRGVLEVVPGYAGGHVPHPTYEEVCTGTTGHREAVQVRFDPGVLPYADLLRYFFAVHDPTSEDRQGPDVGPQYSPAIFYHSEEQKRVAEAVMRELAPLYPKPIATKLLPFTTFYPAEAYHRDYFARHPEAPYCRLVIAPKLEKARKAFKSLLRP MSRA_THET2 TT_P0095