Editing Post-translational modification (section)

===Non-enzymatic additions ''in vitro''===
* [[biotinylation]]: covalent attachment of a biotin moiety using a biotinylation reagent, typically for the purpose of labeling a protein.
* carbamylation: the addition of isocyanic acid to a protein's N-terminus or the side-chain of Lys or Cys residues, typically resulting from exposure to urea solutions.<ref name="stark_1960">{{cite journal |vauthors=Stark GR, Stein WH, Moore X | title = Reactions of the Cyanate Present in Aqueous Urea with Amino Acids and Proteins | journal = J Biol Chem | volume = 235 | issue = 11 | pages = 3177–3181 | year = 1960 | doi = 10.1016/S0021-9258(20)81332-5 | doi-access = free }}</ref>
* oxidation: addition of one or more oxygen atoms to a susceptible side-chain, principally of Met, Trp, His or Cys residues. Formation of [[disulfide]] bonds between Cys residues.
* [[pegylation]]: covalent attachment of [[polyethylene glycol]] (PEG) using a pegylation reagent, typically to the N-terminus or the side-chains of Lys residues. Pegylation is used to improve the efficacy of protein pharmaceuticals.