A comparison of histidine protecting groups in the synthesis of peptide-oligonucleotide conjugates

Abstract Protection of the imidazole ring of the histidine residue is not required for the elongation of an oligonucleotide chain at the side chain hydroxyl group of an amino acid residue by the phosphite triester approach. For the assembly of the peptide chain, the 2,4-dinitrophenyl group is the best alternative when histidine is placed at the C-terminal position.