Extensive circular dichroism studies have been conducted with the title polynucleotides under various solution conditions. The studies provided the following information: (i) The halogen atoms in place of thymine methyl hinder the isomerization into X-DNA. (ii) The brominated but not iodinated polynucleotide isomerizes into Z-DNA in concentrated NaCl+NiCl2. The transition takes place at lower N...

The nucleotide 5'-dGMP and polynucleotide poly(dGdC).poly(dGdC) have been irradiated by using a 200-fs, 200-nm laser pulses and spectrally characterized by using time-resolved infrared spectroscopy. Under the experimental conditions, 200-nm excitation generates both electronic excited states and radical cations through photoionization; the former decay rapidly to vibrationally hot ground state....

graphene nanostructures were synthesized by hummer method. 1, 3, 5 and 7 wt% of graphene nanostructures were suspended in certain amount of acetone on a mechanical stirrer and stirred then added to epoxy resin. after 4 hours, solution and graphene platelets (gps) were prepared. nanostructures were characterized by x-ray diffraction (xrd), scanning electron microscopy (sem ), fourier transform i...

Nickel hydroxide nanostructures were synthesized by a hydrothermal reaction. The effect of different precursors and surfactants on the morphology of nickel hydroxide nanostructures was investigated. Nanostructures were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and Fourier transform infrared  spectroscopy. The influence of Ni(OH)2 nano...

DNA-dependent ATPase IV has been purified to near homogeneity from the Novikoff rat hepatoma. The enzyme is devoid of DNA polymerase, RNA polymerase, exonuclease, endonuclease, phosphomonoesterase, 3'- or 5'-phosphodiesterase, polynucleotide kinase, protein kinase, topoisomerase, helicase or DNA reannealing activities at a detection level of 10(-5) to 10(-7) relative to the ATPase activity. The...

Mononucleotide conformations are important in understanding the structural aspects of nucleic acids and polynucleotides. In order to study the influence of stacking interactions between adjacent bases in a polynucleotide on the preferred conformations of mononucleotides, conformational energy calculations have been carried out on dinucleoside monophosphate fragments. Four base sequences-d(ApT),...

Three polynucleotide phosphorylase mutations, isolated in heavily mutagenized Escherichia coli strains Q7, Q13, and Q27, were characterized after their transfer by P1 transduction to nearly isogenic strains which lack ribonuclease I. Each strain has a different altered form of polynucleotide phosphorylase. One enzyme exhibited sharply reduced activity under all conditions tested. A second had r...

Structural details are reported for a novel right-handed polynucleotide double helix stabilized by vertical base stacking and hydrogen bonding. The primary difference between this duplex and the familiar Watson-Crick horizontally stabilized polynucleotide complex arises in the glycosyl rotation of the heterocyclic bases with respect to the sugar-phate backbone. In the vertical double helix the ...

Two single-stranded polynucleotide constructs, 123 and 126 nucleotides in length, were chemically synthesized using standard phosphoramidite chemistry. Clonable, double-stranded DNA fragments about 100-bp long were prepared from the polynucleotides by primer extension with a DNA polymerase and end-trimming with two restriction endonucleases, then the fragments were ligated into separate plasmid...

The ribosome-inactivating proteins (RIPs) are a family of plant enzymes for which a unique activity has been determined: rRNA N-glycosidase, which removes adenine at a specific universally conserved position (A4324 in the case of rat ribosomes). Here we report that saporin-L1, a RIP from the leaves of Saponaria officinalis, recognizes other substrates, including RNAs from different sources, DNA...