L-leucine residue (2S)-2-amino-4-methylpentanoic acid 0.0 0.0 113.0840606689453125 113.160003662109375 2-azanyl-4-methylpentanoic acid 4-methyl-norvaline A protein modification that effectively converts a source amino acid residue to an L-leucine. C 0 H 0 N 0 O 0 C 6 H 11 N 1 O 1 L L-leucine Leu MOD:00020 PSI-MOD alpha-amino-gamma-methylvaleric acid alpha-aminoisocaproic acid natural residues isobaric at 113.084064 Da natural, standard, encoded residue