DNA Photo-Cross-Linking Using 3-Cyanovinylcarbazole Modified Oligonucleotide with Threoninol Linker

3-Cyanovinylcarbazole modified d-threoninol (D-CNV) was incorporated in oligodeoxyribonucleotide and tested for a photo-cross-linking reaction with complementary oligodeoxyribonucleotide. The photoreactivity was 1.8- to 8-fold greater than that of 3-cyanovinylcarbazole modified deoxyribose (K-CNV) previously reported. From the results of melting analysis and circular dichroism spectroscopy of the duplexes, the relatively flexible structure of D-CNV compared with K-CNV might be advantageous for [2 + 2] photocycloaddition between the cyanovinyl group on the D-CNV and pyrimidine base in the complementary strand.