Oligodeoxynucleotides Modified with 2′-O-(Cysteinylaminobutyl)carbamoylethylribothymidine Residues for Native Chemical Ligation with Peptide at Internal Positions

We used native chemical ligation (NCL) to synthesize a 2 '-O-{N-[N-(S-tert-butylthiocysteinyl)aminobutyl]-carbamoylethyl} (CysBCE) ribothymidine-derived oligonucleotide to expand the variety of peptide conjugation sites, allowing the incorporation of peptides at the 2 '-hydroxy group when the oligonucleotide forms a duplex with the complementary strand. The NCL reaction with a peptide thioester and the modified oligonucleotide proceeded smoothly even when the CysBCE modification was in the middle of the oligonucleotide sequence. In addition, we incorporated two CysBCEs into an oligonucleotide to conjugate two peptides to one oligonucleotide. The results indicated that the tandem NCL reactions proceeded efficiently when the oligonucleotide hybridized to the complementary strand to avoid intramolecular disulfide formation between the two CysBCE groups. This method could be useful for peptide conjugation on the 2 '-position.

Automated summary

In this study, we synthesized a 2'-O-{N-[N-(S-tert-butylthiocysteinyl)aminobutyl]-carbamoylethyl} (CysBCE) oligonucleotide using native chemical ligation (NCL) to expand the variety of peptide conjugation sites. This method allows the incorporation of peptides at the 2'-hydroxy group when the oligonucleotide forms a duplex with the complementary strand. Our results showed that the NCL reaction with a peptide thioester and the modified oligonucleotide proceeded smoothly, even with the CysBCE modification in the middle of the oligonucleotide sequence. Additionally, we successfully conjugated two peptides to one oligonucleotide using two CysBCEs, and the tandem NCL reactions were efficient when the oligonucleotide hybridized to the complementary strand to avoid intramolecular disulfide formation between the two CysBCE groups.