Synthesis and Properties of Oligodeoxynucleotides Possessing N ‐Phosphoryl Groups

This paper deals with the synthesis and properties of oligodeoxynucleotides of a Dickerson−Drew sequence, d(CGCGAATTCGCG), in which one of the four cytosine bases has been replaced with an N ‐phosphorylated or N ‐diethylphosphorylated cytosine base in order to study the effect of the N ‐phosphoryl or N ‐diethoxyphosphoryl group on their structural property and hybridization affinity. The CD spectra of these self‐complementary duplexes showed the typical B DNA‐type shape with very minor changes. In contrast, it was found from T m experiments that N ‐phosphoryl groups destabilized the DNA duplexes significantly through steric hindrance and electronic repulsion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)