One-electron reductive template-directed ligation of oligodeoxynucleotides possessing a disulfide bond

Hypoxic X-irradiation as an external stimulus for conformational change of oligodeoxynucleotides that possess disulfide bond and regulation of DNAzyme function

We achieved a conformational change of oligodeoxynucleotides and the regulation of DNAzyme function by means of a radiolytic strand exchange reaction of disulfide bond. We designed a system in which the DNAzyme function of RNA cleavage was suppressed by the hybridization of an inhibitor strand that possessed disulfide bond with an active DNAzyme. Hypoxic X-irradiation led to the recovery of RNA cleavage because the strand exchange reaction at the disulfide bond in inhibitor strand resulted in a release of inhibitor strand. This strategy may be applicable to gene regulation by hypoxic X-irradiation.

Chemical ligation of oligodeoxynucleotides by X-irradiation and its application to regulation of G-quadruplex formation

We demonstrated radiolytic ligation of oligodeoxynucleotides (ODNs) possessing disulfide bond and its application to regulation of DNA quadruplex formation. G-rich hexamer ODNs had poor ability to form quadruplex, while X-irradiation of the ODNs induced interstrand exchange reaction at disulfide bond to form ligated 12 mer ODNs, leading to the ready formation of quadruplex due to the entropic effect. Since complexation of the ligated ODNs with hemin in the presence of K(+) showed strong soret band absorption and also catalyzed the H(2)O(2)-mediated oxidation of luminol, it appears that the quadruplex formed from ligated ODNs showed a function similar to native DNA quadruplex.

Aggregate formation and radiolytic degradation of amphiphilic DNA block copolymer possessing disulfide bond

We have designed a novel aggregate of DNA block copolymer (DBC) that is sensitive to hypoxic X-irradiation. The DBC consists of tetrahydropyrane-protected 2-hydroxyethyl methacrylate as a hydrophobic unit and oligodeoxynucleotides as a hydrophilic unit, which are linked to a radiation-sensitive disulfide bond. The DBC self-assembled efficiently to form aggregates that encapsulated small molecules such as nile red and pyrene. Hypoxic X-irradiation could then induce reductive degradation of the DBC aggregates via an exchange reaction of the disulfide bond to release guest molecules.

Radiolytic Reduction Characteristics of Artificial Oligodeoxynucleotides Possessing 2-Oxoalkyl Group or Disulfide Bonds

A number of advances have been made in the development of modified oligodeoxynucleotides (ODNs), and chemical or physical properties of which are controlled by external stimuli. These intelligent ODNs are promising for the next generation of gene diagnostics and therapy. This paper focuses on the molecular design of artificial ODNs that are activated by X-irradiation and their applications to regulation of hybridization properties, conformation change, radiation-activated DNAzyme, and decoy molecules.

Radiolytic cyclization of stem-and-loop structured oligodeoxynucleotide with neighboring arrangement of α,ω-bis-disulfides

Upon X-ray irradiation of hypoxic aqueous solution, modified oligodeoxynucleotides (ODNs) bearing a pair of disulfides at both ends of the strand that forms a stem-and-loop structure with a neighboring arrangement of α,ω-bis-disulfides underwent efficient cyclization via an intramolecular exchange reaction at the disulfide moieties with a multiple turnover process. Mechanistic studies revealed that hydrogen atoms generated in the radiolysis of water are key active species initiating a chain reaction to produce cyclic ODN disulfides, in which addition of hydrogen atom results in dissociation of the original disulfide bond to generate a thiyl radical intermediate as the chain carrier for the succeeding disulfide exchange into cyclization. The properties were also assessed for the resultant cyclic ODN disulfide that has several favorable features for use in the transcriptional decoy strategy. The cyclic ODN disulfides produced by the present radiolytic method showed high thermal stability, resistance to nuclease, and high binding activity to a representative transcriptional factor of nuclear factor κB.