2'-modified nucleosides for site-specific labeling of oligonucleotides

DNA three-way junction structures with amino acid side chains prepared via post-synthetic amide condensation

DNA three-way junction (3WJ) structures with three amino acid side chains in the core have been synthesized via post-synthetic DNA modification. Amide condensation reactions of oligonucleotides containing 2'-aminouridine with activated esters yielded DNA strands modified with His, Cys and Asp side chains to form modified 3WJs. Even a 3WJ with three negatively charged Asp side chains formed stably at room temperature. Furthermore, DNA hybridization alone placed two (His and Asp) and three (His, Cys, and Asp) side chains within the 3WJs, indicating that the DNA 3WJs are a useful platform for spatial arrangement of amino acid side chains.

Porphyrin conjugated to DNA by a 2'-amido-2'-deoxyuridine linkage

A porphyrin that contains a single carboxylic acid group was synthesized and coupled to 2'-amino-2'-deoxyuridine. The resultant product contained a free 3' hydroxyl group and a 4,4'-dimethoxytrityl (DMT) protecting group on the 5' hydroxyl of the uridine, making it suitable for use in oligonucleotide synthesis. The 3' H-phosphonate derivative of this molecule was synthesized and used to form a conjugate with a 19 nucleotide sequence of DNA (5'-CCTCCAGTGGAAATCAAGG-3'). This was carried out with the DNA attached at the 3' end to a control pore glass (CPG) substrate, allowing for rapid purification. After removal of the DMT group, an additional three nucleotides were added, leaving the porphyrin as an internal modification. This is the first report of porphyrin attached internally to an oligonucleotide using a hydrogen-bonding nucleoside analog. This allows oligonucleotides to be used as a scaffold for precise positioning of multiple porphyrins within biomimetic arrays.

DNA and LNA oligonucleotides containing N2'-functionalised derivatives of 2'-amino-2'-deoxyuridine

Synthesis of various N-acylated derivatives of 2'-amino-2'-deoxyuridine is described together with their incorporation into DNA and LNA oligonucleotides using the phosphoramidite approach on an automated DNA synthesizer. The thermal stabilities of duplexes formed by these 2'-amino-DNA-modified DNA or LNA/DNA chimeric strands and complementary DNA or RNA strands have been studied. Introduction of LNA monomers around the functionalised 2'-amino-DNA modifications results in reversal of the affinity-decreasing effect of the latter. This represents a novel general approach for design and synthesis of high-affinity functionalised oligonucleotides for biotechnological or medicinal applications.

3'-immobilized probes with 2'-caps: synthesis of oligonucleotides with 2'-N-methyl-2'-(anthraquinone carboxamido)uridine residues

[reaction: see text] A synthesis for oligodeoxynucleotides with a 3'-terminal 2'-N-methyl-2'-acylamido-2'-deoxyuridine residue was developed. Unlike their unmethylated counterparts, these oligodeoxynucleotides can be stably immobilized on aldehyde-displaying glass surfaces to provide DNA microarrays. An anthraquinone carboxamido group as a 2'-substituent doubled the capture efficiency of an immobilized tetradecamer.

Conformationally controlled high-affinity targeting of RNA or DNA by novel 2'-amino-DNA/LNA mixmers and pyrenyl-functionalized 2'-amino-DNA

9-Mer DNA sequences containing 2'-N-methyl-2'-N-(pyren-1-ylmethyl)-2'-amino-DNA monomers display significantly increased affinity towards DNA complements whereas the corresponding 2'-amino-DNA monomer has a detrimental effect on duplex stability. These effects are efficiently reversed by incorporation of four LNA nucleotides inducing a B-DNA to A-DNA conformational change.