N-[(L-histidin-1'-yl)methyl]-L-methionine (fMet) (2S)-2-([(4-[(2S)-2-amino-2-carboxyethyl]-1H-imidazol-1-yl)methyl]amino)-4-(methylsulfanyl)butanoic acid -15.994915008544921875 -16.0 281.107208251953125 281.350006103515625 A protein modification that effectively crosslinks an N-formyl-L-methionine residue and an L-histidine residue to form N-[(L-histidin-1'-yl)methyl]-L-methionine. C 0 H 0 N 0 O -1 S 0 C 12 H 17 N 4 O 2 S 1 Cross-link 2. H, MOD:00030 MOD:01890 N-[(L-histidin-1'-yl)methyl]-L-methionine N-term PSI-MOD hypothetical crosslinked L-histidine residue crosslinked N-formyl-L-methionine residue