monomethylated L-arginine 14.015649795532226562 14.029999732971191406 170.11676025390625 170.220001220703125 A protein modification that effectively replaces one hydrogen atom of an L-arginine residue with one methyl group. C 1 H 2 N 0 O 0 C 7 H 14 N 4 O 1 From DeltaMass: formula incorrect, N and O reversed MOD:00414 Me1Arg Methyl N-methyl Arginyl PSI-MOD R Unimod:34 methylr monomethylated residue methylated arginine