Simple Diaminonucleoside-Mediated Nonenzymatic Ligation of Oligonucleotides

Oligonucleotide-templated chemical ligation is a powerful and robust technique to covalently join two or more oligonucleotides. Chemical handles, such as amino-modifiers, can be incorporated to enhance ligation efficiency. However, their incorporation is typically laborious, expensive, and time-consuming. Utilizing 3',5'-diamino-3',5'-dideoxythymidine (or 3',5'-diamino-2',3',5'-trideoxy-5-methylcytidine) and a water-soluble condensing reagent, we demonstrate a simple and cost-effective methodology for chemically ligating two oligonucleotides containing opposing monophosphate groups in a template-directed manner. Through reaction optimization, product formation reached >85% within 4 h in DNA, RNA-like, and certain chimeric-based systems. Our methodology will find applications in chemical biology and biotechnology.