DNA triplex formation with 5-dimethylaminopropargyl deoxyuridine.

We have prepared triplex-forming oligonucleotides containing the nucleotide analogue 5-dimethylaminopropargyl deoxyuridine (DMAPdU) in place of thymidine and examined their ability to form intermolecular triple helices by thermal melting and DNase I footprinting studies. The results were compared with those for oligonucleotides containing 5-aminopropargyl-dU (APdU), 5-guanidinopropargyl-dU (GPdU) and 5-propynyl dU (PdU). We find that DMAPdU enhances triplex stability relative to T, though slightly less than the other analogues that bear positive charges (T << PdU < DMAPdU < APdU < GPdU).

2'-o-dimethylaminoethoxyuridine and 5-dimethylaminopropargyl deoxyuridine for at base pair recognition in triple helices.

The nucleoside analogues 2'-O-dimethylaminoethoxy uridine and 5-dimethylaminopropargyl deoxyuridine have been synthesised and incorporated into oligonucleotides. Their triplex-stabilising properties have been determined in fluorescence melting experiments.

Synthesis of anthraquinone oligonucleotides for triplex stabilization.

The synthesis of two anthraquinone phosphoramidites is described. In both cases the anthraquinone moiety is attached via a linker to the 5-position of a uracil base, allowing incorporation at any thymidine position in an oligonucleotide sequence. Anthraquinone-modified oligonucleotides have potential applications as triplex stabilizers and fluorescence quenchers.

Triplex staples: DNA double-strand cross-linking at internal and terminal sites using psoralen-containing triplex-forming oligonucleotides.

A method has been developed to attach 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen to the 5 position of thymine bases during solid-phase oligonucleotide synthesis. UV irradiation of triplex-forming oligonucleotides (TFOs) containing internally attached psoralens produces photoadducts at TpA steps within target duplexes, thus relaxing the constraints on selection of psoralen target sequences. Photoreaction of TFOs containing two psoralens, located at the 5'- and 3'-ends, has been used to create double-strand cross-links (triplex staples) at both termini of the TFO.