Synthesis and characterization of phenothiazine labeled oligodeoxynucleotides: novel 2'-deoxyadenosine and thymidine probes for labeling DNA.

A facile procedure for the incorporation of phenothiazine at the terminus of oligodeoxynucleotides is reported. Phenothiazine is covalently linked to the 5'-position of 2'-deoxyadenosine and thymidine. Next, the corresponding phosphoramidites are prepared, and then the labeled nucleosides are incorporated in DNA using an automated DNA solid-phase synthesizer. Phenothiazine labeled oligodeoxynucleotides form stable B-form duplexes with similar melting temperatures, CD spectra, and DSC traces compared to unlabeled DNA duplexes. The favorable photophysical properties of phenothiazine are also retained after covalent attachment to the oligodeoxynucleotide.