Development of antiparallel-type triplex-forming oligonucleotides containing quinoline derivatives capable of recognizing a T-A base pair in a DNA duplex.

A triplex-forming oligonucleotide (TFO) can bind to genomic DNA and inhibit the expression of genes with specific sequences. However, to date, there have been a few reports of modified bases in antiparallel TFOs that can recognize and strongly bind to T-A base pairs. In this study, we introduced several quinoline derivatives into antiparallel TFOs to develop modified bases that can recognize the T-A base pair and evaluated their ability to form triplexes and to discriminate between base pairs. The introduction of 2-acetamido-6-aminoquinoline6DAQac) into an antiparallel TFO allowed the selective recognition of a T-A base pair at both low and high salt concentrations.

Chemical Synthesis of Modified Oligonucleotides Containing 5'-Amino-5'-Deoxy-5'-Hydroxymethylthymidine Residues.

Introduction of cationic modifications into an oligonucleotide can increase its nuclease resistance and duplex- or triplex-forming abilities. In a recent study, we found that the nuclease resistance and RNA binding selectivity of an oligonucleotide containing a 5'-(R)-amino-5'-deoxy-5'-(R)-hydroxymethylthymidine residue were greater than those of the unmodified oligonucleotide. In this article, we describe the synthesis of 5'-amino-5'-deoxy-5'-hydroxymethylthymidine via dihydroxylation of the 5'-alkene derivative using either of two commercial AD (asymmetric dehydroxylation) mixes or via epoxidation and ring opening. We also provide detailed protocols for the syntheses of oligonucleotides containing 5'-amino-5'-deoxy-5'-hydroxymethylthymidine residues. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Synthesis of 5'-amino-5'-deoxy-5'-hydroxymethylthymidine phosphoramidites 9a and 9b Basic Protocol 2: Synthesis of oligonucleotides 1 and 2 containing 5'-amino-5'-deoxy-5'-hydoxymethylthymidine residues (R T and S T).