Nucleosides & nucleotides最新文献

Chimeric oligodeoxynucleotides containing phosphorothioate and N3'-->P5' phosphoramidate linkages were synthesized. These oligomers show a high inhibitory activity against human telomerase.

The effects of cytarabine on the structural and thermodynamic properties of an Okazaki fragment were investigated using UV hyperchromicity and 2D 1H NMR. Cytarabine significantly decreased the stability of this model Okazaki fragment, decreasing the melting temperature from 46.8 degrees C to 42.4 degrees C at 1.33 x 10(-5) M. Cytarabine also markedly increased the bend angle of the Okazaki fragment duplex from 20 degrees to 42 degrees. Changes to the structures and stabilities of Okazaki fragments may cause the biological effects of cytarabine.

The introduction of the base-labile 9-fluorenylmethoxycarbonyl (Fmoc) group into the exocyclic amino function of 2'-deoxynucleosides and their dimethoxytritylation and phosphitylation is described. The resulting key intermediates were investigated in the built-up of different oligodeoxyribonucleoside phosphate and thiophosphate chains which were deprotected under mild basic conditions leading to crude oligomers of high purity.

We investigated the binding and the translation inhibitory properties of hexadecamers complementary to the mini-exon sequence of the protozoan parasite Leishmania amazonensis. This targeted RNA region folds into a hairpin. Large differences were observed in the antisense properties of the different oligomers although their binding to RNA always requires the disruption of the stem region.

Important chemical and biochemical properties of boranophosphate DNA and RNA oligonucleotides are reviewed. Stereoregular boranophosphate oligomers can be synthesized enzymatically and form stable duplexes with DNA. Fully boronated, non-stereoregular oligothymidylates, synthesized chemically, form hybrids with poly(A) that have lower melting points than oligothymidylate:poly(A), yet they nevertheless can support the RNase H mediated cleavage of RNA.

We monitored the binding of triplex-forming oligopyrimidines to the double-stranded stem of the RNA hairpin responsible for the gag-pol frameshift in HIV-1. Whereas the substitution of 5, propynyl-C for C had a limited effect, the use of a Peptide Nucleic Acid 12mer led to a drastic reduction in the stability of the oligomer/RNA complex.

Triplex-stabilizing effect of a graft copolymer under physiologically relevant conditions has been evaluated and compared with other polyamines. Here we show that the graft copolymer significantly stabilizes triplex DNAs with amazingly higher efficacy than that of physiological concentrations of spermine and spermidine.

This paper presents the fully automated solid phase synthesis of 2-5A-PNA hybrids. These stable antisense probes cause RNase L mediated hydrolysis of target RNA sequences.

It was shown that plasmid pUC19 DNA stimulates in vitro proliferation of CBA mouse splenocytes in a dose-dependent manner. Stimulation effect of the plasmid DNA is additive with COn A or LPS, synergistic with PMA and is inhibited by nonimmunogenic phosphodiester oligonucleotides and Fab fragments of antimouse Ig antibodies. These data and the data of affinity labelling of ODN-binding proteins indicate that immunoglobulin receptors are involved in DNA-induced lymphocyte activation.

Various comb-type copolymer containing a polycation as a main chain was design to construct delivery systems of DNAs. The comb-type copolymers having cell-specific polysaccharides were proved to be useful to deliver DNA to the target cells in vivo. Of interest, the copolymers with abundant side chains of hydrophilic polymers are capable of stabilizing DNA triplex. Further, injectable nanoparticles for controlled releases of DNAs were fabricated from the copolymer and a biodegradable polymer.