“…In addition to the above progress, manipulation and understanding the biological function of PTM protein isoform can be achieved through PTM site‐specific installation of covalent PTM modification on wild type proteins 184 . Currently, chemical methods 185,186 or genetic methods have been successfully developed to incorporate many different PTM modifications including phosphorylation, 187,188 glycosylation, 189,190 ubiquitination, lipidation, acetylation, 191 methylation, 192 ADP‐ribosylation, sulfation, 193,194 SUMOylation, 195 nitro alkylation, 196 and oxidation of cysteines 197 . There are three types of chemical biology methods allowing covalent modifications, especially for histone, namely chemical mutagenesis, protein semisynthesis, and genetic code expansion 198 .…”