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....

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...

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...

The acyclic bis-phenanthridinium ligands 1, 2 and the cyclic analogue 3 bind to ss-RNA by bis-intercalation. Due to it’s shorter linker 1 exhibits mono-intercalative binding to ds-polynucleotides, while a mixed mode of binding with 2 is shown to strongly dependent on the base composition and tertiary structure of ds-DNA and RNA. The cyclic analogue 3 binds to ds-polynucleotides by non-intercala...

The gene encoding for polynucleotide phosphorylase (pnp) of a new biovar of Staphylococcus aureus subsp. aureus (NBSA) has been isolated from a genomic library of strain M280(0). The coding region consisted of a 1094-bp HindIII-HindIII DNA fragment encoding for a protein of 277 amino acids with a calculated molecular mass of 29.5 kDa. The nucleotide sequence of the structural gene, contained a ...

1esoxyribonucleoprotein, the genetically active complex of the cell, carries on two important functions: that of self-replication and that of maintaining a cellular environment compatible with its own existence. An adjunct to the latter function among the differentiated cells of the multicellular organism is the accommodation of these processes within individual cells to the needs of the total ...