These results indicate that the spherical fullerene terminus on
the oligonucleotide chain did not hamper duplex and triplex
formation. The cleavage nearly exclusively took place at gua-
nine bases; this is consistent with singlet oxygen mediation. The
same profile of site and base selectivity was observed with an
oligonucleotide-chlorin conjugate (with the same oligonucleo-
tide sequence). which was shown to generate singlet oxygen
upon irradiation and to cleave nucleic acids (results not shown).
In summary, we have shown that fullerene -oligodeoxynucle-
otide conjugates effectively modify
DNA with high site specifici-
ty by forming double and triple helices. The present results
clearly indicate that
fullerene-oligonucleotide conjugates are
promising photoprobes for the investigation of gene transcrip-
tion and mRNA translation. Design of the optimal linker moi-
ety and conditions needed to achieve high efficiency are now
under investigation. In addition, the hydrophobicity
of the
fullerene moiety can be exploited to enhance cell uptake for
biological applications.