Systematic Analysis of 2′-IO/I-Alkyl Modified Analogs for Enzymatic Synthesis and Their Oligonucleotide Properties

Enzymatic oligonucleotide synthesis is used for the development of functional oligonucleotides selected by in vitro selection. Expanding available sugar modifications for in vitro selection helps the functional oligonucleotides to be used as therapeutics reagents. We previously developed a KOD DNA polymerase mutant, KOD DGLNK, that enzymatically synthesized fully-LNA- or 2′-O-methyl-modified oligonucleotides. Here, we report a further expansion of the available 2′-O-alkyl-modified nucleotide for enzymatic synthesis by KOD DGLNK. We chemically synthesized five 2′-O-alkyl-5-methyluridine triphosphates and incorporated them into the oligonucleotides. We also enzymatically synthesized a 2′-O-alkyl-modified oligonucleotide with a random region (oligonucleotide libraries). The 2′-O-alkyl-modified oligonucleotide libraries showed high nuclease resistance and a wide range of hydrophobicity. Our synthesized 2′-O-alkyl-modified oligonucleotide libraries provide novel possibilities that can promote the development of functional molecules for therapeutic use.