Peptide custom synthesis>Methylation modification is a highly prominent modification method in terms of biological and physicochemical properties among other common post-translational modifications (PTMs). It can occur in at least 9 of the 20 common amino acid residues (Met, Cys, Lys, Arg, His, Gln, Asn, Glu, and Asp), while the most common methylation/demethylation mainly occurs on the lysine (Lys) and arginine (Arg) side chains, and is involved in almost all biological processes, such as regulating cellular functions such as transcription, cell division, and cell differentiation. Methylation modification can occur at different amino acid sites or generate more than one methylation modification at the same amino acid site. Methyl-peptide