Anthracene-DNA conjugates as building blocks of designed DNA structures constructed by photochemical reactions.

We present the photochemical ligation of anthracene-ODN (oligodeoxyribonucleotide) conjugates through cycloaddition of anthracenes. Anthracene-DNA conjugates were synthesized by linking the 5'- or 3'-end of ODNs to the anthracene group. The sequences of the conjugates were designed to hybridize to neighboring sites on the target ODN with their anthracene units facing each other. When the ternary duplex consisting of the two conjugates and the target forms, the conjugates can be dimerized by light irradiation. The dimerization efficiency was affected by the substitution position of the anthracene group and by a one-base displacement in the template sequence. Furthermore, it is demonstrated that the capping of the duplex and connecting third strands in a triplex structure could also be the target of the photochemical ligation.