title: Azide-alkyne cycloaddition for universal post-synthetic modifications of nucleic acids and effective synthesis of bioactive nucleic acid conjugates.
abstract: The regioselective post-synthetic modifications of nucleic acids are essential to studies of these molecules for science and applications. Here we report a facile universal approach by harnessing versatile phosphoramidation reactions to regioselectively incorporate alkynyl/azido groups into post-synthetic nucleic acids primed with phosphate at the 5' termini. With and without the presence of copper, the modified nucleic acids were subjected to azide-alkyne cycloaddition to afford various nucleic acid conjugates including a peptide-oligonucleotide conjugate (POC) with high yield. The POC was inoculated with human A549 cells and demonstrated excellent cell-penetrating ability despite cell deformation caused by a small amount of residual copper chelated to the POC. The combination of phosphoramidation and azide-alkyne cycloaddition reactions thus provides a universal regioselective strategy to post-synthetically modify nucleic acids. This study also explicated the toxicity of residual copper in synthesized bioconjugates destined for biological systems.
authors.affiliation: Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan. tzupinw@cc.kmu.edu.tw.
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Su
authors.forename: Yu-Lun
authors.initials: YL
authors.lastname: Lo
authors.forename: Chi-Ching
authors.initials: CC
authors.lastname: Hwang
authors.forename: Li-Fang
authors.initials: LF
authors.lastname: Wang
authors.forename: Min Hui
authors.initials: MH
authors.lastname: Wu
authors.forename: Eng-Chi
authors.initials: EC
authors.lastname: Wang
authors.forename: Yun-Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Tzu-Pin
authors.initials: TP
authors.lastname: Wang
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry; D001386:Azides / Q000737:chemistry*; D001692:Biological Transport; D002384:Catalysis; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D057930:Click Chemistry; D003300:Copper / Q000737:chemistry; D061565:Cycloaddition Reaction; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009696:Nucleic Acids / Q000737:chemistry*; D009841:Oligonucleotides / Q000138:chemical synthesis* / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D010756:Phosphoric Acids / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D000577:Amides; D001386:Azides; D009696:Nucleic Acids; D009841:Oligonucleotides; D010455:Peptides; D010756:Phosphoric Acids; D003300:Copper; C011067:phosphoramidic acid