alkylated residue methylated residue A protein modification that effectively replaces a hydrogen atom with a methyl group. From DeltaMass: Average Mass: 14 Average Mass Change:14 References:Methylation of Asparagine (found in phycobiliproteins) Klotz and Glazer (1987) J. Biol. Chem. 262; 17350-17355 MOD:00427 MeRes Methylation (N terminus, N epsilon of Lysine, O of Serine, Threonine or C terminus, N of Asparagine) PSI-MOD