Triple Helix
Mostrando 37-48 de 281 artigos, teses e dissertações.
-
37. Collagen triple-helix formation in all-trans chains proceeds by a nucleation/growth mechanism with a purely entropic barrier
Collagen consists of repetitive Gly–Xaa–Yaa tripeptide units with proline and hydroxyproline frequently found in the Xaa and Yaa position, respectively. This sequence motif allows the formation of a highly regular triple helix that is stabilized by steric (entropic) restrictions in the constituent polyproline-II-helices and backbone hydrogen bonds betwee
National Academy of Sciences.
-
38. A physico-chemical study of triple helix formation by an oligodeoxythymidylate with N3'--> P5' phosphoramidate linkages.
Non-denaturing gel retardation assay, DNA melting experiments and FTIR spectroscopy were used to characterize the triple helix formed by a 15mer 2'-deoxythymidylate with N3'-->P5'phosphoramidate linkages with its target sequence. The results indicate that: (i) the pentadecadeoxythymidylate with phosphoramidate linkages [dT15(np)] is highly potent to form a t
-
39. Sequence-specific recognition of the major groove of DNA by oligodeoxynucleotides via triple helix formation. Footprinting studies.
Homopyrimidine oligodeoxynucleotides recognize the major groove of the DNA double helix at homopurine.homopyrimidine sequences by forming local triple helices. The oligonucleotide is bound parallel to the homopurine strand of the duplex. This binding can be revealed by a footprinting technique using copper-phenanthroline as a cleaving reagent. Oligonucleotid
-
40. Exclusion of RNA strands from a purine motif triple helix.
Research concerning oligonucleotide-directed triple helix formation has mainly focused on the binding of DNA oligonucleotides to duplex DNA. The participation of RNA strands in triple helices is also of interest. For the pyrimidine motif (pyrimidine.purine.pyrimidine triplets), systematic substitution of RNA for DNA in one, two, or all three triplex strands
-
41. Potassium-resistant triple helix formation and improved intracellular gene targeting by oligodeoxyribonucleotides containing 7-deazaxanthine.
Triple helix formation by purine-rich oligonucleotides in the anti-parallel motif is inhibited by physiological concentrations of potassium. Substitution with 7-deazaxanthine (c7X) has been suggested as a strategy to overcome this effect. We have tested this by examining triple helix formation both in vitro and in vivo by a series of triple helix-forming oli
-
42. Intramolecular triplex potential sequence within a gene down regulates its expression in vivo.
Polypurine/polypyrimidine sequences have been shown to adopt intramolecular triple helix structures under torsional stress and/or at low pH. Such sequences have been observed within the the regulatory as well as the coding regions of several genes and the involvement of triple helical structure adopted by these sequences in transcriptional control has been s
-
43. Quinazoline-2,4(1H,3H)-dione as a substitute for thymine in triple-helix forming oligonucleotides: a reassessment.
A major limitation in triple-helix formation arises from the weak energy of interaction between the third strand and the double-stranded target. We tried to increase the stacking interaction contribution within the third strand by extending the aromatic domain of thymine. We report here the use of 2,4-quinazolinedione as a substitute for thymine in the canon
-
44. Padlock oligonucleotides for duplex DNA based on sequence-specific triple helix formation
An oligonucleotide was circularized around double-stranded DNA thanks to triple helix formation. Short oligonucleotides are known to be able to form DNA triple helices by binding into the DNA major groove at an oligopurine⋅oligopyrimidine sequence. After sequence-specific recognition of a double-stranded DNA target through triple helix formation, the ends
The National Academy of Sciences.
-
45. An anti-parallel triple helix motif with oligodeoxynucleotides containing 2'-deoxyguanosine and 7-deaza-2'-deoxyxanthosine.
Triple helix formation of oligodeoxynucleotides (ODNs) with a 15 base pair poly-purine DNA target in the HER2 promoter was examined by footprinting analysis. 7-deaza-2'-deoxyxanthosine (dzaX) was identified as a purine analogue of thymidine (T) which forms dzaX:A-T triplets. ODNs containing 2'-deoxyguanosine (G) and dzaX were found to form triple helices in
-
46. Inhibition of T7 and T3 RNA polymerase directed transcription elongation in vitro.
A class of oligonucleotides which binds to naturally-occurring duplex DNA sites at physiologic pH to form triple helical structures was used as transcription attenuators in an in vitro transcription assay. Oligonucleotides were designed to form triple helices with a purine-rich, double-stranded target by binding in the major groove in an orientation anti-par
-
47. Optimization of alternate-strand triple helix formation at the 5"-TpA-3" and 5"-ApT-3" junctions.
Alternate-strand triple helix formation was optimized at the two junction steps, the 5"-TpA-3" and 5"-ApT-3" junctions. Footprint experiments, gel retardation assays and thermal denaturation measures on a sequence appropriately designed with two adjacent alternate-strand polypurine tracts points out that the addition of an adenine residue and the removal of
-
48. Structural features and stability of an RNA triple helix in solution.
A 30 nt RNA with a sequence designed to form an intramolecular triple helix was analyzed by one-and two-dimensional NMR spectroscopy and UV absorption measurements. NMR data show that the RNA contains seven pyrimidine-purine-pyrimidine base triples stabilized by Watson-Crick and Hoogsteen interactions. The temperature dependence of the imino proton resonance