Enzymatic and chemical synthesis of isodeoxynucleic acid (INA) and its properties.

Isodeoxynucleic acid (INA) is one of the most attractive sugar modified nucleic acids for therapeutic use. We report here the enzymatic synthesis and properties of INA. All four isodeoxynucleoside triphosphates (INTPs) were synthesized for use in a single nucleotide insertion reaction. K(m) and V(max) values showed the almost same order as natural dNTPs. Primer extension reactions were also carried out to investigate the function of INTPs as substrates for several DNA polymerases. INTPs were incorporated into N + 2 position. One INTP and three dNTPs were able to generate a full-length product (27 mer). These results suggested that template-primer duplex containing one isodeoxynucleoside could be recognized by DNA polymerases. However, duplexs containing more than two isodeoxynucleosides could not be recognized by DNA polymerases because of conformational changes by isodeoxynucleosides.