نتایج جستجو برای: triplex ultrasound
تعداد نتایج: 110149 فیلتر نتایج به سال:
New methods for the preparation of reversible pH-responsive DNA hydrogels based on Hoogsteen triplex structures are described. One system consists of a hydrogel composed of duplex DNA units that bridge acrylamide chains at pH = 7.4 and undergoes dissolution at pH = 5.0 through the reconfiguration of one of the duplex bridging units into a protonated CG·C+ triplex structure. The second system co...
New methods for the preparation of reversible pH-responsive DNA hydrogels based on Hoogsteen triplex structures are described. One system consists of a hydrogel composed of duplex DNA units that bridge acrylamide chains at pH 1⁄4 7.4 and undergoes dissolution at pH 1⁄4 5.0 through the reconfiguration of one of the duplex bridging units into a protonated CG$C triplex structure. The second system...
Synthesis of a BQQ-neomycin conjugate is reported. The conjugate combines two ligands, one known to intercalate triplexes (BQQ) and another known to bind in the triplex groove (neomycin). The conjugate stabilizes T.A.T, as well as mixed base DNA triplex, better than neomycin, BQQ, or a combination of both. The conjugate selectively stabilizes the triplex (in the presence of physiological salt c...
Oligonucleotides provide novel reagents for inhibition of gene expression because of their high affinity binding to specific nucleotide sequences. We describe a 38 base, single-stranded DNA that forms a triple helix or 'triplex' on progesterone response elements of a target gene. This triplex-forming oligonucleotide binds with a Kd = 100 nM at 37 degrees C and physiological pH, and blocks bindi...
A conformational distortion in the DNA duplex at the regulatory region of human papillomavirus type-11 next to an intermolecular triplex, formed with a synthetic oligonucleotide, was investigated with several chemical probes. The sequence targeted for triplex formation borders on the binding sites for the regulatory proteins encoded by the viral E2 open reading frame. Dimethyl sulfate, diethyl ...
OBJECTIVES We report on a study of thoracic aortic replacement in a canine model in order to demonstrate experimentally the process of tissue healing facilitated by the uniquely structured Triplex® graft. METHODS Twelve Triplex® grafts were used in this study with 12 collagen-coated vascular grafts (Hemashield®, Boston Scientific, Natick, MA, USA) as the controls in 24 dogs; the grafts were t...
Peptide nucleic acid (PNA) modified with unnatural nucleobases enables the formation of a highly stable triplex with a double-stranded RNA at physiological pH. In this communication, we evaluated kinetics and thermodynamics of PNA/RNA triplex formation as a function of both pH and temperature. Protonation entropy was found to be the major factor responsible for the destabilization of the triple...
Calorimetric and fluorescence techniques were used to characterize the binding of aminoglycosides-neomycin, paromomycin, and ribostamycin, with 5'-dA(12)-x-dT(12)-x-dT(12)-3' intramolecular DNA triplex (x = hexaethylene glycol) and poly(dA).2poly(dT) triplex. Our results demonstrate the following features: (1) UV thermal analysis reveals that the T(m) for triplex decreases with increasing pH va...
Natural polyamines, i.e. putrescine, spermidine and spermine, are excellent promoters of triplex DNA. Using melting temperature (Tm) measurements and CD spectroscopy, we found that structural alterations on spermidine backbone, including methylation, or acetylation at the N1-, N4- and/or N8-positions had a profound influence on the stability and conformation of poly(dA).2poly(dT) triplex. The c...
We report a complete thermodynamic characterization of the stability and the melting behavior of an oligomeric DNA triplex. The triplex chosen for study forms by way of major-groove Hoogsteen association of an all-pyrimidine 15-mer single strand (termed y15) with a Watson-Crick 21-mer duplex composed of one purine-rich strand (termed u21) and one pyrimidine-rich strand (termed y21). We find tha...
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