The synthesis and properties of oligodeoxyribonucleotides containing N6-methoxyadenine

Abstract
Oligodeoxyribonucleotides containing N6-methoxy-adenine (M) have been synthesized. The order of stability of duplexes consisting of synthesized oligodeoxyribonucleotides, 5d(CCTGGTAXCAGGTCC)3-5′d(GGACCTGNTACCAGG)3′ (X = M, A, G. N = A, G, T, C), was M: A (Tm = 52°C) >M: T (50°C) >M: G (48°C) >M: C (46°C) observed by thermal denaturation in a buffer of 0.01 M Na cacodylate, and 0.1 M NaCI at pH 7.0. The Tms are within a range of 6 degrees of difference, which Is smaller than those of Tms of the duplexes containing A:N pairs (11 degrees) and G:N pairs (11 degrees). DNA replication study on a template-primer system, 5′d(32P-CAGCTTTCGC)3′ 3′d(GTCGAAAGCGMAGTCG)5′,showed that TTP and dCTP were incorporated into DNA strands at a site opposite to M by Klenow DNA polymerase, but dATP and dGTP were not.