Phenothiazine as a redox-active DNA base substitute: comparison with phenothiazine-modified uridine.

Phenothiazine can be incorporated as a redox-active probe into DNA in two conceptually different ways: the non-nucleosidic DNA base surrogate exhibits similar properties to 10-methylphenothiazine but with no preferential base-pairing properties, whereas the phenothiazine-modified uridine has different optical and electrochemical properties, but exhibits preferred Watson-Crick base pairing with adenine.