Common types of bioconjugation reactions on proteins are coupling of lysine, cysteine, and tyrosine amino acid residues, as well as modification of tryptophan residues and of the N- and C- terminus.
Bioconjugation reactions typically target specific sites on proteins for attachment, including amino acids like lysine, cysteine, and tyrosine, as well as the ends of the protein chain (N- and C-termini) and sometimes tryptophan residues.